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# Length, Weight, and Time Units for Firefighter Exam Study Guide (page 3)

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Updated on Jun 30, 2011

### Calculating with Length, Weight, and Time Units

On the test, you may be asked to add or subtract length, weight, and time units. The only trick to doing this correctly is to remember to convert the smaller units to larger units and vice versa, if need be.

Example: Example: Find the perimeter of the figure:

To add the lengths, add each column of length units separately:

Since 27 inches is more than 1 foot, the total of 16 feet 27 inches must be simplified:

• Convert 27 inches to feet and inches:
• 27 inches × feet = 2 feet 3 inches

Finding the length of a line segment may require subtracting lengths of different units. For example, find the length of line segment

To subtract the lengths, subtract each column of length units separately, starting with the rightmost column.

Warning: You can't subtract 8 inches from 3 inches because 8 is larger than 3! As in regular subtraction, you have to borrow 1 from the column on the left. However, borrowing 1 ft. is the same as borrowing 12 inches; adding the borrowed 12 inches to the 3 inches gives 15 inches. Thus:

Add and simplify. Answers are at the end of this chapter.

1. Subtract and simplify.

2. Now, try these time word problems.

3. At the beginning of your shift you have been assigned to run a calibration test on the company's three gas meters. Each test took you 50 minutes. Just as you are finishing, the captain brings in another meter from the chief 's office. When you finish that calibration, you find that you have spent a total of hours on this assignment. How long did it take to calibrate the fourth meter?
1. hour
2. hour
3. 1 hour
4. hours
4. The total person-hours spent at a hazardous materials incident is 9 hours and 20 minutes, and a total of 20 firefighters are assigned. What is the average time per firefighter?
1. 35 minutes
2. hour
3. 0.28 hours
4. 28 minutes

1. 24
2. 120
3. 48
4. 2
5. 8 feet
6. 13 pounds. 10 ounces
7. 1 foot 8 inches
8. 1 hour 53 minutes
9. b.
10. c.