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3. Time
In this chapter you will learn about:
• calculating and problem solving with time
• elapsed time
• time zones and the International Date Line
3.1 Working with Seconds, Minutes,
and Hours
In this section, you will solve problems with seconds, minutes,
and hours.
Get Ready
You will need:
•stopwatch
Exercise 3.1
Warm Up
1 Work out:
a 60 + 60 =
c 115 – 60 =
?
?
b 75 – 60 =
?
d 93 – 60 =
?
64
e 80 = 60 +
g The first ten multiples of 60 are:
f 75 = 60 +
?
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?
60, 120, 180,
h
1
2
?
,
?
,
?
i
of 60 ,
1
4
?
,
of 60
2 Here are the results for a 400 m falcon race:
Name of falcon
Time in seconds
Azzam
19.2
Mirfooq
21.3
Barood
21
Waddah
19.4
Dagaash
19
a In a race, does the winner have the
longest or shortest time?
b Which falcon was the fastest?
c Which falcon was the slowest?
dWhat was the difference between the times
for 1st and 2nd places?
3 1 minute
1 second
Which is the shortest?
Which is the longest?
1 hour
65
?
,
?
,
?
4 How many:
a seconds in 1 minute?
b minutes in 1 hour?
c hours in 1 day?
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5 Copy and complete this sequence:
60,
?
, 180, 240,
?
,
?
, 420,
?
6 Copy and complete this table:
Hint
Use your sequence from Q5 to help you.
1 minute
?
seconds
2 minutes
?
seconds
3 minutes
?
seconds
4 minutes
?
seconds
5 minutes
?
seconds
10 minutes
?
seconds
1 hour
?
minutes
1
2
?
minutes
7 Copy and complete this table:
hour
?
1
1 2 hours
120 minutes
?
minutes
?
180 minutes
?
600 minutes
66
,
?
,
?
Main Exercise
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8 Work out:
a65 seconds =
?
minute
b130 seconds =
?
minutes
?
seconds
c362 seconds =
?
minutes
?
seconds
d128 minutes =
?
hours
?
minutes
e246 minutes =
?
hours
?
minutes
?
seconds
Hint
Use your
table from
Q7 to help
you.
9Add:
a30 seconds + 40 seconds
=
minute
?
seconds
?
seconds =
?
minute
?
seconds
?
minutes =
?
hour
?
minutes
d63 minutes + 57 minutes
=
?
c30 minutes + 48 minutes
=
seconds =
b45 seconds + 45 seconds
=
?
?
minutes =
?
hours
?
minutes
e39 minutes + 32 minutes
=
?
minutes =
?
hour
67
?
minutes
10Match the correct time to each activity. Write your answers in your
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notebook.
Activity 1 Activity 2
Activity 3
Activity 4
a 1.5 hours b 30 minutes c 15 seconds d 1 minute
11Gathering and Recording Information
N
DSITO
N
Y
A
H ACtiV In pairs.
Use a stopwatch.
68
a Copy this table into your notebook:
Time in seconds
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Calculation
Name:
Name:
1
?
?
2
?
?
3
?
?
4
?
?
5
?
?
Total time:
?
?
bThe first person times their partner. Time how long your partner
takes to work out each calculation in their head:
1 60 + 45
2 75 – 34
3 60 – 28
4 30 × 4
5 15 × 5
Write the times in your table, under your partner’s name.
cThe second person times their partner. Time how long your
partner takes to work out each calculation in their head:
1 30 + 83
2 68 – 47
3 60 – 27
4 30 × 5
5 25 × 5
Write the times in your table.
d Check your partner’s answers on a calculator. Work out the total
times for correct answers only.
Hint
Did your partner take longer than 60 seconds?
Then write the time as ? minutes ? seconds.
e
Make up your own 5 calculations. Repeat steps a–d.
K TAOL
T
UT I
AB
fWhich is more important in mathematics: being fast
or being correct?
69
12Faisal and his friends are
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learning to juggle a football
with their feet.
Each boy has 2 turns.
Name
Turn 1
Turn 2
Total time
Ahmed
31 seconds
34 seconds
1 minute
5 seconds
Mubarak
31 seconds
47 seconds
?
Salem
28 seconds
42 seconds
?
Faisal
45 seconds
38 seconds
?
a Calculate the total time for each boy.
b Who had the shortest total time?
cWrite the boys’ total times in order from shortest to longest.
dWork out the difference between the shortest and longest
total times.
Hint
Mubarak’s time = 31 seconds + 47 seconds =
= ? minute ? seconds.
?
seconds
We can write hours as h, minutes as min and seconds as s.
1 h = 60 min.
70
135 separate journeys take the following times:
d 14 h 55 min + 6 h 23 min
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a 44 min + 27 min
b 57 min + 19 min
e 7 h 25 min + 3 h 39 min
c 3 h 28 min + 5 h 47 min
Work out the total time taken for each of the journeys.
Hint
You can add the minutes first to see if they equal more than
1 hour (60 minutes).
14A school has a morning assembly. Work out the total times.
Write your answers in your notebook.
a The students sing the national anthem for 2 min 40 s.
Then they listen to the Qur’an for 3 min 48 s.
Hint
?
min
?
s+
?
min
?
s=
b The students exercise for 3 min 32 s.
Then the Principal speaks for 2 min 17 s.
71
?
.
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c Grade 6 certificates are given out for 4 min 45 s, Grade 7 certificates for 2 min 52 s and Grade 8 certificates for 3 min 28 s.
d What was the total length of the morning assembly?
Example
Zayed went to football practice.
30 min driving to football practice
1 h 25 min
playing football
How long was Zayed away from home altogether?
72
45 min in the car
going home
Answer
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Step 1 Change 1h 25 min into minutes.
60 min + 28 min = 85 min
Step 2 Add all the minutes each activity took.
30 min + 85 min + 45 min = 160 min
Step 3 Work out the time in hours and minutes using
repeated subtraction.
160 – 60 (1 hour) =100
100 – 60 (1 hour) = 40
Step 4 Add the number of hours to the remaining minutes.
It took 2 h 40 min altogether.
Main Exercise
15How long did each group of activities take altogether?
aReading
Watching TV
Playing football
1h
1 h 40 min
75 min
b
35 min boat ride
1 h 25 min snorkeling c Preparing paper and paints
Painting
Cleaning paints and brushes
73
45 min boat ride
back to beach
20 min
2 hours 15 min
25 min
16Work out in hours (h) and minutes (min) the total time
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for each subject:
a English: 4 periods of 45 minutes each
b Math: 6 periods of 50 minutes each
c History: 5 periods of 30 minutes each
dScience: 4 periods of 40 minutes each
plus a 1-hour practical lesson
Hint
You can use
repeated
subtraction to
convert minutes
to hours.
17Saif watched TV for 2 hours. He saw an advertisements every
5 minutes. How many advertisements did he see?
18Mona studied for 3 hours, including short breaks. Every 40 minutes
she took a 5-minute break. How many breaks did she take?
19A school has parent–teacher meetings. Each meeting is around
3 minutes long. How many parent-teacher meetings can take place
in 1 hour?
20Faisal takes the bus to school, and home again every school day.
Each journey takes him 25 minutes.
How long does Faisal spend on the bus every week?
INK
TH
T IT
BOU
A
21Gathering and Recording Information
a Record how many hours you sleep each night for one week.
Copy and complete a table like this:
Night
Sun
Mon
Tue
Wed
Thur
Fri
Sat
Number
of hours
sleeping
?
?
?
?
?
?
?
bHow long did you sleep in total?
Give your answer in days and hours.
cExplain how you worked out your
answer to Qb.
74
Hint
24 hours = 1 day.
1 month =
about 30 days.
22Making Decisions Read this information:
eenagers need between 9 and 10 hours of sleep every night.
T
Not getting enough sleep can affect your academic and sporting
performance. It may also increase your risk of emotional problems.
Even 30 minutes of extra sleep each night makes a difference.
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D REOA
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Look at your table in Q21.
Do you think you are getting enough sleep? Explain your decision.
23Estimate how long you spend asleep in:
a one month
b one year
c ten years
Explain in your own words how you worked out your answer.
24Afra spent 1 hour 20 minutes sculpting with clay. She made 4 pots.
She spent the same time on each pot.
How long did each pot take?
Hint
Try changing the time into minutes first.
25Nasser spends 2 hours playing
computer games.
He divides his time equally between 3 games.
How much time does he spend on each game?
265 groups perform harbiya
dancing at a festival.
The total performance is
1 hour 10 minutes.
Each group performs for the
same length of time.
How long does each group
perform?
75
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27For a fireworks show:
• the length of the show is 15 minutes
INK
T
TH
I
T
U
ABO
• a small firework goes off every 20 seconds
• a larger firework goes off every 45 seconds.
a How many fireworks are needed?
b Explaining Explain how you solved the problem.
Hint
Use this timeline to help you see the pattern:
Min 0
Sec
2
1
10 20 30 40 50
10 20 30 40 50
= Small firework
3
10 20 30 40 50
4
10 20 30 40 50
= Large firework
76
5
10 20 30 40 50
3.2 Working with Months and Years
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In this section, you will solve problems with months, years, decades,
and centuries.
You will use timelines.
Get Ready
You will need:
•calendar
Exercise 3.2
Warm Up
1 Copy and complete each sequence:
Hint
Use multiplication to help you.
a 7, 14, 21,
b 4, 8, 12,
c 12, 24, 36,
?
,
?
?
,
?
,
?
,
?
,
?
,
?
,
?
77
,
?
,
:
7 days =
1 week.
?
,
Math fact
?
,
?
,
?
,
?
,
?
,
?
,
?
,
?
?
,
?
2 How many days in:
b 3 weeks
c 4 weeks
d 5 weeks
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a 2 weeks
3 Organizing Information Use a calendar.
Write the answers in your notebook.
a Copy and complete the table:
Month
Number of days
Complete weeks
Extra days
January
31
4
3
February
28 (29 in a leap year)
?
?
March
31
?
?
April
30
?
?
May
31
?
?
June
30
?
?
July
31
?
?
August
31
?
?
September
30
?
?
October
31
?
?
November
30
?
?
December
31
?
?
b What is the total number of days in a year?
c Add the complete weeks column. What is the total?
d Add the extra days column. How many weeks do they add up to?
e How many weeks are there altogether?
78
Main Exercise
Math fact
:
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4 How many months in:
a 2 years
c 5 years
12 months
=
1 year.
b 3 years
d half a year
5 Identifying Patterns Compare the number of
days in each month.
Is a month exactly 4 weeks?
Why do you think we say a month is about 4 weeks?
6Work out and write each answer in weeks and days.
a 5 days + 6 days
Hint
5 days + 6 days =
?
days =
?
week
?
days.
b 3 days + 11 days
c 12 days + 11 days
d 3 days + 21 days
e 6 days – 4 days
f 1 week – 3 days
Hint
1 week – 3 days = 7 days – 3 days =
?
days.
g 3 weeks – 12 daysh 2 weeks 1 day – 9 days
7 Abdulla is visiting UAE from Oman.
He spends 13 days in Dubai and then 4 days in Abu Dhabi.
Then he flies home to Oman.
How long is Abdulla’s visit?
79
8 Grade 7B has four tests in May:
Mon
Tues
Wed
Thurs
Fri
Sat
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
27
28
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Sun
MATH
TEST
SOCIAL
STUDIES
TEST
22
ENGLISH
TEST
23
24
25
26
ARABIC
TEST
29
30
31
How many weeks and days are there between:
a the Math test and the Social Studies test?
b the English test and the Arabic test?
c the Math test and the English test?
9 Maitha’s family is going on a tour of Egypt. They will spend:
• 2 days at Aswan
• 1 day traveling to Egypt
• 2 days at Lake Nasser
• 3 days in Cairo
• 1 day traveling home
• 3 days in Alexandria
• 2 days in Luxor
80
aHow long is the trip
Mediterranean Sea
altogether?
Alexandria
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Cairo
b
Maitha’s family travels to
Egypt on Tuesday.
On which day will they
arrive in:
iAlexandria?
iiLuxor?
iiiAswan?
EGYPT
Red
Sea
Luxor
Lake
Nasser
Aswan
10A company is building a new mall. It will take:
• 6 months to fit the shops
• 3 months to select an architect
• 2 months to complete
• 1 year to design the mall
• 18 months to build the mall
a How long does it take before the mall can open?
bHow much longer does it take to build the
mall than to fit the shops?
11Copy and complete this table:
Years
Months
Weeks
?
?
52
4
?
?
?
6
?
1 12
?
?
?
36
?
Hint
Work out the years first.
81
Math fact
1 year =
52 weeks.
:
12A company is making a new movie.
They spend:
• 4 months planning
• 18 months doing research
• 6 months writing a script
• 8 months filming
• 4 months editing
How long does it take to make the movie altogether?
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Hint
Remember
1 year = 12 months.
13Generating Solutions
Design a calendar for the 2015–2016 school year.
There must be at least 180 days of school altogether.
You can choose if school will be open or closed in Ramadan
(7 June – 6 July 2016).
Public holidays (no school):
Eid al Adha 23–28 September 2015
Islamic New Year 13 October 2015
National Day holiday 2–3 December 2015
New Year’s Day
1 January 2016
Isra’a and Miraj
5 May 2016
Eid Al Fitr
7–9 July 2016
Math fact
1 decade =
10 years.
1 century
=
100 years
.
:
14Copy and complete the table:
a
b
Decades
1
2
3
4
5
8
17
Years
10
20
?
?
?
?
?
Centuries
1
2
3
4
5
9
20
Years
100
200
?
?
?
?
?
82
Aysha
11 years
Aunt
42 years
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Father
38 years
Mother
35 years
Salma
3 years
Suhail
13 years
Grandfather
70 years
15How many years older is:
a Grandfather than Aunt?
Hint
Hint
Grandfather’s age – Aunt’s age =
?
.
b Father than Aysha?
c Suhail than baby Salma?
d Mother than Aysha?
e Aunt than Suhail?
16a How many decades has Grandfather been alive?
b How many decades has Aunt been alive?
c Has anyone in the family been alive for a century?
83
17aLaila joins the army. Her basic training takes 16 weeks.
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How many days is the training?
Hint
16 × 7 =
?
Use partitioning
7
10
6
?
?
b Rashid attends a photography course. It takes 24 weeks.
How many days is the course?
cMira attends a first aid course. It takes 18 weeks.
How many days is the course?
18How many months in:
a 2 years?
b 3 years?
c 5 years?
d half a year?
19Identifying Relationships Hamda says, ‘1 month = 4 weeks’.
Look at a calendar. Compare the number of days in each month.
What would you say to Hamda?
These were the public holidays in the UAE for 2014:
• January 1: New Year’s Day
• January 12: the Prophet Muhammad’s (PBUH) birthday *
• May 26: Israa and Miraj night *
• June 28: Ramadan expected to begin *
• July 28: Eid Al Fitr *
• October 3: Waqfat Arafat *
• October 4: Eid Al Adha *
• October 25: Hijri New Year *
• December 2 and 3: National Day
84
Use a calendar to help you work out your answers.
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20Approximately how many months:
a from New Year’s Day to Waqfat Arafat?
b from Israa and Miraj night to Eid Al Fitr?
c from Eid Al Fitr to Hijri New Year?
d from Waqfat Arafat to National Day?
Word fact
:
Approxim
ately
‘about’ or ‘c means
lose to’.
Your answ
er does no
t
have to be
exact.
21How many weeks:
a from Eid Al Fitr to Waqfat Arafat?
b from New Year’s Day to Hijri New Year?
c from Israa and Miraj night to Hijri New Year?
22Explaining Look at the list of public holidays.
Some of them have a star (*) beside them,
but others do not.
Explain why.
23Copy and complete this table:
Years
Decades
Centuries
a
30
?
?
b
50
?
?
c
?
40
?
d
?
?
13
e
?
50
?
f
?
?
8
?
?
g 1 200
85
Math fact
10 years =
1 decade.
100 years
=
1 century.
:
24aIbrahim looks after turtles. One of them is 80 years old.
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How many decades is this?
Hint
80 ÷ 10 =
?
decades.
bHessa goes to the museum.
She sees a sword that is 260 years old.
How many decades is this?
25How many centuries, decades and years between:
a 1500 and 1800?
Hint
1500
1800
b 1600 and 2000?
c 1600 and 1950?
d 1789 and 1999?
e 1895 and 2014?
Explain in your own words how you worked out your answer.
86
26A tree stood from 1725 until 2010.
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How long did the tree live?
Write your answer in centuries,
decades and years.
27Which is the oldest building?
Al Jahili Fort – built in 1898
Al Badiyah Mosque – built in 1446
Qasr Al Husn – built 1761
Sharjah Fort – built in 1820
28How many decades passed between the dates
when these buildings were built:
a Qasr Al Husn and Sharjah Fort?
b
Sharjah Fort and Al Jahili Fort?
c Qasr Al Husn and Al Jahili Fort?
87
Hint
First count whole decades.
Then give your answer in
decades and years.
29How many centuries passed between the dates when these
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buildings were built:
a
Qasr Al Husn and Al Jahili Fort?
b Al Badiyah Mosque and Al Jahili Fort?
Math fact
:
30Below is a timeline showing some
important events in the history of football.
A timeline
is a
number lin
e showing
units of tim
e. It shows
you when
things
happened.
Which letter shows each event?
1970
A
1975
1980
1985
1990
1995
2000
B
2005
2010
C D E
a The UAE Football Association is established in 1971.
b UAE qualifies for the FIFA World Cup in 1990 with Egypt.
c UAE wins the 2005 Kirin Cup.
d UAE hosts the FIFA U-20 World Cup in 2003.
e Gulf Cup of Nations is held in Abu Dhabi in 2007.
31Use your answers to work out.
a How many years between B and D?
b How many years between:
• qualifying for the FIFA World Cup with Egypt and
•hosting the FIFA U-20 World Cup?
c Which year was four decades after B?
88
2015 32 Organizing Information
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The A380 Airbus
Here are some important events in the history of the A380 airbus.
A J une 1988 – Airbus engineers start work on an ultra-high-capacity airliner
(UHCA)
B J une 1994 – Airbus announces plan to develop a large airliner called the
A3XX
C D
ec 2000 – Airbus votes to launch 8 billion Euro programme to build the
A3XX
D Jan 2005 – First A380 unveiled in Toulouse, France
E J une 2005 – Airbus announces delay in deliveries
F O
ct 2007 – First A380 flight with Singapore Airlines
G A
ugust 2008 – Emirates receives A380 for Dubai-New York flight
H M
ay 2014 – Etihad Airlines reveals A380I – June 2014 – Qatar Airlines
receives A380
Draw a timeline for the years 1985 to 2015.
Mark the events A to H on your timeline.
33How many years between:
a A and B?b C and D?c G and H?
34 How many decades between:
a A and G?
b B and H?
35How many months between:
a D and E?b F and G?c E and F?
d H and I?
36Explaining Explain in your own words how you worked out your
answers.
89
3.3 Elapsed Time
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In this section, you will solve problems calculating the start and end
times of events. You will also work out how long activities take.
Get Ready
You will need:
•analog clock face with
movable hands
•
digital clock
Warm Up
1 How many minutes in:
a
1
2
3
4
hour?
b
1
4
:
60 minute
s=
1 hour.
d2 12 hours?
c
e1 34 hours? f4 14 hours?
hour?
Math fact
hour?
90
2 Are these times: A – morning or B – afternoon/evening?
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Hint
Times between midnight and 11:59 am are morning.
Times from 12:00 to 11:59 pm are afternoon/evening times.
a 8:45 am
b 7:15 pm
c 1:30 pm
d 2:20 am
e 11:17 am
f 3:30 pm
g 9:58 pm
h 6:00 am
Math fact
:
Math fa
ct:
Digital cloc
ks can sho
w 24-hour
time. At m
idnight, th
e time is
00:00.
1 o’clock in
the
morning is
01:00.
1 o’clock in
the
afternoon
is 13:00.
20:30 is th
e same
as 8.30 pm
.
After 23:5
9 at night,
the time
ticks to 00
:00 again,
and the ne
xt day beg
ins.
am = morn
ing.
pm = after
noon
and evenin
g.
3 Are these times: A – morning (am), B – afternoon/evening (pm)?
a13:24
b16:18
c06:59
d11:42
e00:00
f02:32
g17:38
h 14:01
91
4Show the times on an analog clock.
Then show the time 1 hour later.
Word fact
:
Later mea
ns after.
So one hou
r later
means +1
hour.
Earlier me
ans before
.
One hour e
arlier
means –1 h
our.
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HAANCtiVITY
a 7:00 am
b 3:20 pm
c 8:23 pm
d 11:10 am
5 Write the time 2 hours earlier.
a 6:00 pm
b 3:47 pm
c 1:13 pm
d 2:30 am
Main Exercise
Example
Zayed gets on the bus at 8:30 am.
He travels for 4½ hours.
What time does he get off the bus?
Answer
Step 1 Look at the start time. 8:30 am is the start time.
Step 2 Add the hours.
8:30 am + 4 hours = 12:30 pm.
Step 3 Add the minutes.
12:30 pm + 30 min = 1:00 pm.
Step 4 Write the end time.
It ends at 1:00 pm.
+ 4 hours
+ 30 minutes
pm
pm
am
0
00
1:
:3
12
30
8:
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6 Work out the end times of each bus trip:
Trip length
a
10:30 am
2 hours
b
9:15 am
7 hours
c
11:15 am
5½ hours
d
10:35 am
4 hours 40 minutes
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Start time
Hint
Use a timeline
with the start time.
Add the hours.
Then add the
minutes.
Here are movie times at a cinema:
Movie
Jungle Adventure 2
Running time: 101 minutes
Star Journey
Running time: 85 minutes
Ice World
Running time: 108 minutes
The Block People Movie
Running time: 100 minutes
Time
10:15
15:00
19:15
11:00
13:00
14:55
16:40
10:45
13:45
16:45
19:45
18:45
11:15
7 What time does each movie end:
a The 10:15 showing of Jungle Adventure 2?
b The 13:00 showing of Star Journey?
c The 18:45 showing of Star Journey?
d The 19:15 showing of Jungle Adventure 2?
Example
The 11:15 movie ends at 13:05.
What is the running time?
93
Word fact
:
Running t
ime is the
length of a
movie in
minutes.
We also ca
ll it
duration.
Here is one way to work it out:
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Answer
Step 1 Draw a time line.
5
:0
13
5
:1
11
Mark the start time 11:15 and the end time 13:05.
+ 45 minutes
0
:0
12
5
:1
11
+ 45 minutes
+ 1 hour
0
:0
13
0
:0
12
5
:1
11
Step 2 Count the minutes to the next hour.
+ 45 minutes
+ 1 hour
+ 5 minutes
5
:0
13 00
:
13
0
:0
12
5
:1
11
Step 3 Count the hours to 13:00.
Step 4 Count the rest of the minutes.
Step 5 Add all the minutes and the hours.
45 min + 1 hour + 5 min = 1 hour 50 min.
Step 6 Write the running time of the movie.
1 hour 50 min.
94
Here is another way:
1 hour
5 minutes
5
:0
13 00
:
13
0
:0
12
5
:1
11
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45 minutes
or
45 minutes
1 hour 5 minutes
5
:0
13 00
:
13
0
:0
12
5
:1
11
8 Generating Solutions Hamdan is studying for exams.
• He gets home from school every day at 3:15 pm.
• He rests for 20 minutes before he starts studying.
• He needs 1 hour 15 minutes each day for homework.
• He stops from 6 pm–7:45 pm to have dinner and pray.
• He goes to bed at 9:30 pm.
•How much time can Hamdan spend on extra study in one week
(5 days, Sunday to Thursday)?
Hint
Make a timetable for Hamdan’s day.
95
Look at the bus timetable for the Abu Dhabi X60 bus.
INK
TH
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BOU
A
Madinat Zayed
Abu Dhabi
Bus Station
Bus Station
1
2
3
4
Mezaira’a
Mussafah
Bus Station
Bus Station
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X60
Departure time
Saturday – Thursday
1
2
Arrival time
Arrival time at Terminus
Friday/Public Holiday
3
4
1
2
3
4
0510 0555 0605 0750 0820
0510 0555 0605 0750 0820
0710 0755 0805 0950 1020
0710 0755 0805 0950 1020
0910 0955 1005 1150 1220
0910 0955 1005 1150 1220
1110 1155 1205 1350 1420
1110 1155 1205 1350 1420
1310 1355 1405 1550 1620
1310 1355 1405 1550 1620
1510 1555 1605 1750 1820
1510 1555 1605 1750 1820
1710 1755 1805 1950 2020
1710 1755 1805 1950 2020
1910 1955 2005 2150 2220
1910 1955 2005 2150 2220
9 How many minutes does it take:
a Mezaira’a Bus Station Madinat Zayed Bus Station?
b Madinat Zayed Bus Station Mussafah Bus Station?
c Mezaira’a Bus Station Abu Dhabi Bus Station?
10aHow long is the wait between arriving at Madinat Zayed Bus
Station and leaving for Mussafah Bus Station?
b How long does it take?
Mezaira’a Bus Station Show how you worked out your answer.
Abu Dhabi Bus Station?
c
Explaining If you arrive at Stop 1, what is the longest waiting
time for the next bus? Explain how you worked out your answer.
96
11Eman takes 25 minutes to get from home to the bus stop.
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She wants to catch the 9:10 am bus.
What is the latest she should leave home?
Hint
Use a timeline.
Count the minutes back to the nearest hour.
12
itIeT
wr
T
BOU
A
Write three math questions (in words) for your partner
using the time on this clock.
Check your partner’s answers.
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3.4 Time Zones and the International
Date Line
In this section, you will learn about the need for time zones and the
International Date Line. You will also learn about using time zones in
everyday life.
Get Ready
You will need:
• globe showing the world map
•torch
D
REOA
T
UT I
AB
It takes 24 hours for the Earth to make a full turn.
The Sun stays still.
Day
As the Earth turns, half of
the Earth is in sunlight and it
is day.
The other half of the Earth is
in shadow and it is night.
Night
N
Sun’s rays
It cannot be daytime all over
the Earth at the same time.
S
When you wake up at 7:00 am in the UAE, it is different times in other
parts of the world. Time zones tell us the difference between the time in
one place and another.
98
Word fact
:
The four co
mpass
directions
are north,
south, eas
t, and wes
t.
Exercise 3.4
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Warm Up
1Stand the globe on a flat surface.
N
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HAANCtiVITY
Point a pencil straight towards Abu Dhabi.
aName three countries to the east of the UAE.
b Name three countries to the west of the UAE.
2Use your globe and torch to show how the Earth turns in one day.
N
DS O
HAN iVITY
ACt
Show how half the Earth moves into daylight while the other half
moves into night.
3Here are the times in some other places when it is 9 am in the UAE.
a Copy and complete the table below.
bFor each place, write whether it is
Hint
Ahead means it is
later than in UAE.
Behind means it is
earlier than in UAE.
ahead or behind UAE time.
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Place
Time when it is
9 am in UAE
Ahead or behind
UAE?
Riyadh, Saudi Arabia
8 am
?
Johannesburg, South Africa
7 am
?
Perth, Australia
1 pm
?
Buenos Aires, Argentina
2 am
?
San Francisco, USA
9 pm
?
Brisbane, Australia
3 pm
?
c
Explaining Use your world globe.
Shine your torch directly at the UAE
Hint
(to show midday). What do you notice Use east and west
about the places that are ahead of the
in your answer.
UAE? What do you notice about the
places that are behind?
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Main Exercise
This map shows some of the world time zones.
Can you see the time zones?
As you move east, you add an hour for each time zone.
As you move west, you subtract an hour for each time zone.
–2
–1
London
0
+1
+2
+3
Berlin
+4
+5
+6
Abu Dhabi
+7
+8
+9
+10
Bombai
+11 +12– –11
Oslo
Moscow
International Date Line
London
Rome
Beijing
Beijing
Palestine
Tokyo
Tehran
Cairo
Hong Kong
Abu Dhabi
Bombai
Dakar
Lagos
Nairobi
Prime Meridian
Johannesburg
–2
–1
0
Tokyo
Sydney
+1
+2
+3
+4
+5
+6
Sydney
+7
+8
Toronto
100
+9
+10 +11 +12– –11
Frankfurt
4
Identifying Patterns Look at the map of the world time zones.
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Describe the patterns you can see.
5aFind the UAE on the map. Move to the east, to the next time zone.
Name a place in this time zone.
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c From the UAE, move five time zones to the east.
d How many hours do you add to UAE time?
e From the UAE, move three time zones to the west.
f How many hours do you subtract from UAE time?
UTC means Coordinated Universal Time. London is in the UTC time
zone. The UAE is UTC + 4. We are 4 hours ahead of London and UTC.
Example
What time is it in Bangkok, Thailand when it is 5:30 pm in Abu Dhabi?
Answer
Find out which time zone Bangkok is in.
Time zone UTC +7
Work out how many hours ahead. Bangkok = UTC +7.
Abu Dhabi = UTC +4.
7–4=3
Bangkok = 3 hours ahead
of Abu Dhabi.
Add on 3 hours to 5:30 pm. 5:30 pm + 3 hours = 8:30 pm.
Write the answer.It is 8:30 pm in Bangkok when
it is 5:30 pm in Abu Dhabi.
101
6
Gathering and Recording Information Use the internet to help you.
List the time zones of the following places. Then work out the time in
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eLearning each place when it is 5:30 pm in Abu Dhabi.
a Harare, Zimbabwe
b Los Angeles, USA
c Sydney, Australia
7Gathering and Recording Information Use the internet to help you.
eLearning a Choose one city on each continent and list its time zone.
b Find the time in that city when the time is midnight in Abu Dhabi.
Hint
Use a number line to help work out the difference
between time zones.
–4
–3
–2
–1
0
+1
+2
Sào Paulo
+3
+4
Abu Dhabi
8In your own words, tell your partner why we need to have different
K
TAOL
T
UT I
AB
time zones.
9A hotel has clocks that show the times in Abu Dhabi, London,
Cape Town, San Francisco, Auckland and New York.
Abu Dhabi
London
Cape Town
San Francisco
Auckland
New York
Use the time zones to help you copy and complete the table on the
next page.
Abu Dhabi UTC +4
Cape Town UTC +2
Auckland UCT +12
London UTC
San Francisco UTC –8
New York UTC –5
102
London
San Francisco
Auckland
New York
2:30 pm
?
?
?
?
?
7 am
?
?
?
?
?
?
midnight
?
?
?
?
?
9:00 pm
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Abu Dhabi
10These clocks are from another hotel.
a
b
c
d
e
Match the clocks to the correct cities. Use the time zones below to help you.
Tokyo UTC+9
Hong Kong UTC +8
Sydney UTC +10
Nairobi UTC +3
11Makkah Al Mukaramah (Holy Makkah) is
the home of the world’s largest clock.
The clock shows the time at
Arabia Standard Time,
which is UTC +3.
Explaining Is the time in
Makkah Al Mukaramah
(Holy Makkah) earlier
or later than the time in
the UAE?
Explain your answer.
103
Cape Town +2
The International Date Line
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The world is divided into 24 time zones.
We can think about the UTC time zone (e.g. London) as the ‘middle’.
Imagine it is 12 pm on Monday in London.
We can count around the world in both directions to find the times in
other time zones.
London
UTC
London
UTC
–3
UTC
–4
UTC
–2
UTC
–1
UTC
UTC
+1 UTC
+2
UTC
–5
9 am
Mon
8 am
Mon
UTC
+3
UTC
+4
7 am
Mon
UTC
+5
UTC
–6
11 am 12 pm 1 pm
10 am Mon Mon Mon 2 pm
Mon
Mon
5 pm
Mon
6 am
Mon
UTC
+6
3 pm
Mon
4 pm
Mon
6 pm
Mon
7 pm
Mon
5 am
Mon
4 am
Mon
3 am
Mon
2 am
Mon 1 am
Mon
?
8 pm
Mon
9 pm
Mon
10 pm
11 pm Mon
Mon
12 am on Monday?
12 am on Tuesday?
What do we do where the two sides meet?
London
UTC
• On the left side of the diagram, the times get earlier and earlier,
11 am 12 pm 1 pm
Mon
so the next time should
be
amMonon2 pm
Monday.
Mon12
10 am
Mon
Mon
am
3 pm get later and later,
• On the right side of9Mon
the diagram, the times
Mon
am
4 pm
so the next time 8should
be
12
am
on
Tuesday!
Mon
Mon
7 am
pm
• To solve this problem,
the countries of the 5world
agreed
Mon
Mon
to create an International
Date Line.
6 am
6 pm
Mon
It is an imaginary line that goes through theMon
middle of the
7 pm
5 am
time zone opposite
UTC.
Mon
Mon
8
pm
4
am
It marks the change
from one day to the next.
Mon
Mon
3 am
Mon
2 am
Mon 1 am
Mon
12 am on Monday
9 pm
Mon
10 pm
11 pm Mon
Mon
12 am on Tuesday
104
International
Date Line
12 am on Monday?
12 am on Tuesday?
London
UTC
Math fact
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11 am 12 pm 1 pm
10 am Mon Mon Mon 2 pm
Mon
Mon
9 am
Mon
8 am
Mon
:
3 pm
Mon
4 pm
Mon
7 am
Mon
If you cros
Internation s the
al Date Lin
moving ea
e
st, the time
is the
same, but
you subtra
c
t 1 day.
If you cros
s the Inter
n
a
tional
Date Line
moving we
st,
the time is
the same,
but you ad
d 1 day.
5 pm
Mon
6 am
Mon
6 pm
Mon
7 pm
Mon
5 am
Mon
4 am
Mon
3 am
Mon
2 am
Mon 1 am
Mon
12 am on Monday
8 pm
Mon
9 pm
Mon
10 pm
11 pm Mon
Mon
12 am on Tuesday
International
Date Line
12Copy and complete the table:
Tonga
UTC +12
American
Samoa
UTC −12
3:00 pm on
Monday
3:00 pm on
Sunday
?
2:30 pm on
Tuesday
11:00 am on
Thursday
?
?
4:25 am on
Friday
7:59 am on
Wednesday
?
Midnight on
Saturday
?
Marshall
Islands
PACIFIC OCEAN
Solomon
Islands
Fiji
Australia
Tonga
American
Samoa
International
Date
Line
New Zealand
105
Samoa
Tahiti
13For each journey say whether you add a day or subtract a day.
a Fiji to American Samoa
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b American Samoa to the Solomon Islands
c Sydney to Tahiti
d Marshall Islands to American Samoa
14Explaining Faisal says:
Hint
Use your globe and
torch to help.
‘At any moment, are there two
days on Earth at the same time?’
Is he correct?
15Write down when you might use time zones in real life.
Use the pictures to help you.
a
b
c
106
Example
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Here is the departure board for some of the flights leaving from
Abu Dhabi Airport
INK
TH
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BOU
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DEPARTURES
Flight number
Departure time
Destination
Flight length
EY131
11:00
Washington, DC
14 h 50 min
EY204
15:40
Mumbai
2 h 45 min
AZ3912
21:45
Bahrain
41 min
EY454
22:00
Sydney
14 h 10 min
SA7603
22:10
Johannesburg
7 h 40 min
The time zones are:
Abu Dhabi UTC +4
Mumbai UTC +5:30
Sydney UTC +10
Washington DC UTC –5
Bahrain UTC +3
Johannesburg UTC +2
Use this information to calculate the local time in Washington when flight
EY131 lands.
Answer
Step 1 Work out the landing time in Abu Dhabi.
Departure time + flight length = landing time.
Flight EY131 departs at 11:00 and the flight is 14 h 50 min.
You can use a timeline to help you:
+12 hours
+2 hours
107
0
:5
01 0
:0
0
:0
0
:0
The flight arrives at 01:50 Abu Dhabi time.
01
23
11
+50 minutes
Step 2 Work out what the local time is in Washington.
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– 9 hours
01:50
–5
–4
–3
–2
–1
0
+1
+2
+3
+4
Local time is 16:50:
a in Mumbai when flight EY204 lands
b in Bahrain when flight AZ3912 lands
c
in Sydney when flight EY454 lands
d Johannesburg when flight SA7603 lands.
16Saeed’s cousins live in Washington, DC.
INK
TH
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BOU
A
He wants to chat to them on a video call.
Saeed’s cousins are at school Monday to Friday from 8:00 am
until 4:00 pm.
Saeed is at school Sunday to Thursday from 7:00 am
until 2:00 pm.
aResearch the time difference between
e Le a r n i n g
Abu Dhabi and Washington.
b What is a possible time for an online video chat:
at the weekend?
during the week?
108
!
Summary
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The main units of time are seconds, minutes, hours, days, weeks,
months, and years.
60 seconds = 1 minute
24 hours = 1 day
4 weeks = 1 month
1 decade = 10 years
60 minutes = 1 hour
7 days = 1 week
12 months = 1 year
1 century = 100 years
We can use analog clocks, digital clocks and timelines to help us
work out time units.
am means morning and pm means afternoon or evening.
On the 24-hour clock, we count hours from 00:00 to 23:59.
Elapsed time is the time that has passed from when an event started to
when it finished.
Start time
Elapsed time
Finish time
We can use timelines to help us work out elapsed time.
Time zones tell us the difference between the times at different places
on Earth. The UAE is at UTC +4. As we move east, we add an hour for
each additional time zone. As we move west, we subtract an hour.
The International Date Line is an imaginary line that runs from north to
south. If you cross the dateline moving east, you subtract a day. If you
cross it moving west, you add a day.
109
Review
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1 Amna goes to the mall. She spends:
• 42 min driving to the mall
• 7 min parking
• 28 min at the supermarket
• 15 min at the pharmacy
• 27 min at the shoe shop
• 38 min at the bank
• 50 min driving home.
aHow much time does Amna spend driving and parking altogether?
bHow much longer does she spend at the bank than at the
supermarket?
cHow much time does the whole journey take?
Give your answer in hours and minutes.
dMake up your own question for a partner to answer.
Check each other’s answers.
2
Sultan goes to football practice three times per week.
Each practice is 90 minutes long.
aHow many hours per week does Sultan spend at football
practice?
bHow many hours in four weeks does he spend at football
practice?
3Ali has three hours to study for an exam.
He wants to study five chapters of work.
He will spend an equal amount of time on each chapter.
How much time can Ali spend on each chapter?
110
4 Here is a schedule for Dubai Satellite Channel TV:
Monday 12 May
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Time
Show
3:00 pm
UAE News
3:30 pm
Football – Al Ain Club vs Al Wahda Club
5:00 pm
Sports News
5:30 pm
World News
6:00 pm
Shaabiat Al Cartoon
6:30 pm
Arabs’ Got Talent
7:30 pm
Freej
8:00 pm
Football – Al Dhafra Club vs Al Ahli Club
8:30 pm
Local News
a How long is the UAE News?
b How long is Arabs’ Got Talent?
cSalem watches the Sports News, World News and Shaabiat Al
Cartoon. How long does he spend watching TV altogether?
d Which program starts 2½ hours after the UAE News starts?
eHamdan watches from the start of the Al Ain Club vs Al Wahda
Club football game until the end of Freej.
How much time does Hamdan spend watching TV altogether?
5aKhalifa catches the bus at 6:40 am.
He gets to school at 7:15 am.
How long is the bus trip?
bMansour takes 46 minutes to get to school.
He needs to arrive at school by 7:55 am.
What is the latest he should leave?
c Explain how you solved problems a and b.
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6 Copy and complete the table.
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Use the time zones in the box to help you.
Boston, USA UTC –5
Edinburgh, UK UTC
Anchorage, Alaska, USA UTC –9
Cairo, Egypt UTC +2
Boston
Anchorage
Edinburgh
Cairo
?
?
?
4:45 pm
2:17 am
?
?
?
?
?
8:58 pm
?
?
12 noon
?
?
7 Copy and complete the table.
Tonga
American Samoa
1:15 pm on Tuesday
?
?
12:30 pm on Thursday
4:25 pm on Wednesday
?
112
I can statements
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What can you do?
• I can add and subtract units of time.
• I can multiply and divide units of time.
• I can explain how I solved time problems.
• I can work out the end time of an event.
• I can work out how long an event took.
• I can explain how I solved problems about how long something took.
• I can work out times using international time zones.
• I can work out times using the International Date Line.
• I can explain what a time zone is.
113