1.What is the joint frequency of students who have chores and a
curfew? Which marginal frequency is the largest?
Curfew: YES Curfew: NO
Total
Chores:YES 13
5
18
Chores: NO
12
3
15
Total
25
8
33
Problem Task
3. Use the frequency table below to answer the following questions.
Youth Soccer League
2. Judy collected information about the type of sports that students
in her school were involved in. She recorded her information in
the frequency table below.
Male
Female
a.
b.
c.
d.
Basketball
25
23
Soccer
30
32
Tennis
15
20
Gender
3-5
yrs old
6-8
yrs old
M
F
Total
4
1
5
3
4
7
Age Group
9-11
12-14
yrs old yrs old
3
3
6
5
4
9
15-17
yrs old
Total
5
3
8
20
15
35
a.) What is the relative frequency of players who are male and 9-11
years old? (joint relative frequency)
b.) What is percentage of female players that are 15-17 years old?
(conditional relative frequency)
c.) What percentage of league members are male? (marginal relative
frequency)
No Sports
45
40
What percentage of females play tennis?
What percentage of males are not involved in any sport?
What percentage of students play soccer?
What percentage of students are male and play soccer?
4. Use the frequency table to answer the following questions.
a. Given that a league member is female, how likely is she
to be 9-11 years old?
b. What is the probability that a member is aged 9-11?
c. Given that a league member is aged 9-11, what is the
probability that a member of this league is a female?
d. What is the probability that a league member is female?
e. Are the events “9-11 years old” and “female” independent? Justify your answer.
5. Use the table below to determine if being a girl and never having a part-time job
are independent or dependent events. Then approximate the probability that a
student is a girl, given that the student never had a part-time job.
6. Skill-based task:
From the table, determine the probability of getting the flu,
and compare that to the probability of getting the flu given that
an individual takes high doses of vitamin C.
Placebo
Vitamin C
Total
Cold
31
17
48
No cold
109
122
231
total
140
139
279
7. Problem Task:
Life is like a box of chocolates. Suppose your box
of 36 chocolates have some dark and some milk
chocolate, divided into cream or nutty centers. Out
of the dark chocolates, 8 have nutty centers. Out of
the milk chocolates, 6 have nutty centers. Onethird of the chocolates are dark chocolate. What is
the probability that you randomly select a chocolate
with a nutty center? Given that it has a nutty center,
what is the probability you chose a dark chocolate?
Show how you determined your answers.
Your turn! Turn in your answers on a separate sheet of paper.
Use the following frequency table to answer #1 – 3:
1) Find P(democrat and supports the issue)
2) Find P(democrat | supports the issue)
3) Error analysis: A student calculated the
relative frequency of those who do not support
the issue, given that they are Republican, as
33
≈ 0.478. What error did the student make?
69
4) Fill in the two way frequency table by using the given information.
(Categories)
Car
Truck
Totals
5)
6)
7)
8)
9)
Red
12
10
?
Blue
?
?
13
Totals
?
15
?