January 05, 2012
Review: Estimate the sum or difference by
rounding to the nearest half dollar.
1. $9.13 - $4.62
2. $7.63 - $5.49
3. $12.13 - $8.37
4. $16.53 - $2.75
5. $18.50 + $6.19
6. $35.71 + $18.29
January 05, 2012
Objectives:
1. Find and compare precision of
measurements
January 05, 2012
Vocabulary:
-Precision: the degree of exactness
January 05, 2012
When measuring objects, you should make sure
that you are measuring using appropriate units.
For example, it would not be appropriate to
measure the length of a stapler in miles!
1. capacity of car's gas tank:
ounces
gallons
2. length of a marathon road race:
miles
feet
3. weight of a horse:
grams
kilograms
4. weight of a baseball:
ounces
pounds
5. length of an eyelash:
meters
millimeters
6. Why do the answers that we chose make sense?
January 05, 2012
As stated before, the precision of a
measurement refers to the degree of exactness.
The marks, or the scale, on the tool used to
measure tell us the precision that is possible.
January 05, 2012
Each mark on this oven thermometer represents
25 F. That means that measurements taken
are precise only to the nearest 25 F. Any
measurement made in smaller increments would
be an estimation, and not precise.
January 05, 2012
What is the greatest precision possible with the
inch ruler above?
January 05, 2012
What is the greatest precision possible with
the inch ruler above?
January 05, 2012
Which ruler was more precise:
1/8 inch or 1/16 inch? Explain
your answer
January 05, 2012
Choose the more precise measurement:
a) 12 fl oz
or
2c
b) 3 L
or
2.5 L
c) 9.8 km
or
7.87 km
d) 25.5 g
or
11 g
January 05, 2012
We know that 12 in. = 1 ft
Does that mean that 12 in and 1 ft have the
same preciseness? Why or why not?
January 05, 2012
Sometimes when we are solving problems, we
will be adding or subtracting measurements that
have different levels of preciseness. For
example: 16.9 L + 13.25 L
When doing calculations like this, your
calculation can only be as precise as the least
precise measurement, so we will need to round
to the least precise measurement.
16.9 + 13.25 = 30.15 but the least precise
measurement was 16.9 so we need to round to
the nearest tenth. Our answer would be 30.2 L
January 05, 2012
Find each sum or difference: Remember to
round to match the least precise measurement
a) 8.4 g + 5 g
b) 9.97 cm - 5.9 cm
c) 45 m - 0.9 m
d) 11.4 g + 2.65 g
e) 2 L + 1.75 L
January 05, 2012
What does it mean to round your answer to the
less precise measurement?