# Choosing and Converting Units ```COURSE 3 LESSON 5-2
Choosing and Converting Units
Use dimensional analysis to convert 0.7 mi to ft.
0.7 mi =
=
0.7 mi
5,280 ft
•
1
1 mi
Multiply by a conversion factor.
Divide by the common units.
(0.7)(5,280) ft
1
Simplify.
Simplify.
= 3,696 ft
There are 3,696 ft in 0.7 miles.
5-2
COURSE 3 LESSON 5-2
Choosing and Converting Units
A rowing team completed a 2,000-m course at a
rate of 6.84 m/s. Convert this rate to kilometers per minute.
Estimate 6.84
7. Then, 7 • 60 &divide; 1000 = 0.42.
6.84 m
6.84 m
1 km
=
•
•
1s
1s
1000 m
60 s
1 min
(6.48)(1)(60) km
Multiply by two ratios that
each equal one.
Divide by the common units.
= (1)(1,000)(1) min
Simplify.
= 0.4104
Use a calculator.
The team rowed at a rate of 0.4104 km/min.
Check for Reasonableness The answer 0.4104 km/min is close to the
estimate 0.42. The answer is reasonable.
5-2
COURSE 3 LESSON 5-2
Choosing and Converting Units
Use compatible numbers to estimate the number
of gallons in 33 quarts.
1 gal
The conversion factor for changing gallons to quarts is 4 qt .
Round to the nearest number
33 qt 32 qt
divisible by 4.
=
32 qt
1 gal
•
1
4 qt
Multiply by the conversion factor.
Divide by the common units.
32
= 4 gallons
Simplify.
= 8 gallons
Divide.
There are about 8 gallons in 33 quarts.
5-2
COURSE 3 LESSON 5-2
Choosing and Converting Units
1. Choose an appropriate customary unit and metric unit for the distance
between two cities.
miles; kilometers
2. Convert 0.75 hours to seconds.
2,700 s
3. \$150 per hour is how much per minute?
\$2.50 per min
4. 69.2 cm is about how many meters?
0.7 m
5-2
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