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# Length, Weight, and Time Units for Firefighter Exam Study Guide (page 2)

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Updated on Jun 30, 2011

The questions involving length, weight, and time on the math test will ask you either to convert between different measurement units or to add or subtract measurement values.

### Common Terms

You may encounter questions that expect you to understand basic geometric concepts, such as the following:

• perimeter: the distance around a two-dimensional figure. To determine the perimeter of a shape, add the lengths of each side.
• square footage: unit of measurement used to define the size of an area. To determine the square footage of a rectangular area, multiply length by width.

### Converting

You may encounter questions that ask you to convert between units of measurement in length, weight, or time. To convert from a smaller unit (such as inches) to a larger unit (such as feet), divide the smaller unit by the number of those units necessary to equal the larger unit. To convert from a larger unit to a smaller unit, multiply the larger unit by the conversion number.

Example: Convert 36 inches to feet.
• Since 1 foot = 12 inches, divide 36 by 12: 36 ÷ 12 = 3 feet
Example: Convert 4 feet to inches.
• Since 1 foot = 12 inches, multiply 4 by 12: 4 × 12 = 48 inches
Example: Convert 32 ounces to pounds.
• Since 1 pound = 16 ounces, divide 32 by 16: 32 ÷ 16 = 2 pounds
Example: Convert 2 pounds to ounces.
• Since 1 pound = 16 ounces, multiply 2 by 16: 2 × 16 = 32 ounces
Example: Convert 180 minutes to hours.
• Since 1 hour = 60 minutes, divide 180 by 60: 180 ÷ 60 = 3 hours
Example: Convert 4 hours to minutes.
• Since 1 hour = 60 minutes, multiply 4 by 60: 4 × 60 = 240 minutes

Now try some on your own. Convert as indicated.

1. 2 feet = _____ inches
2. 2 hours = _____ minutes
3. 3 pounds = _____ ounces
4. 120 minutes = _____ hours.

### 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:

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:

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.