5.6.1 Self-Check on Units of Measurement

Exercise symbolExercise 1: Units of Measurement in the U.S.

For each of the following scenarios, use the appropriate operation and unit to determine the answer.

Soccer ball

(a) At the start of soccer practice, the water jug contained 16 quarts of water. Five players each drank one quart, and two players drank two quarts each. How much water was left over at the end of practice?

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(a) Quarts of water left =   equation sequence 16 minus five multiplication one minus two multiplication two equals 16 minus five minus four equals 11 minus four equals seven

(b) At birth, Peter weighs 7 pounds 9 ounces. During his first two days at the hospital, he loses 3 ounces each day. After he returns home, he gains 8 ounces. How much does Peter weigh now?

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(b) So Peter’s weight now = 7 pounds + 9 ounces – 2 multiplication 3 ounces + 8 ounces

                                         = 7 pounds + 9 ounces – 6 ounces + 8 ounces

                                         = 7 pounds + 3 ounces + 8 ounces

                                         = 7 pounds + 11 ounces

Peter now weighs 7 pounds 11 ounces.

(c) A rectangular garden measures 12.4 feet by 18.3 feet. How much fencing will need to be purchased to enclose the garden?  How much is this in yards?

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multiline equation line 1 12 times 21 times .4 line 2 18 full stop three line 3 12 .4 line 4 separator plus plus 18.3 low line line 5 61.4

(c) To enclose the garden 61.4 feet of fencing will need to be purchased.

1 yard = 3 feet

So length of fencing = 61.4 feet ÷ 3 = 20.5 yards (to 1 d.p)

In yards 20.5 yards of fencing will need to be purchased.

Exercise symbol Exercise 2: Units of Measurement in the Metric System (SI)

After riding a roller coaster ride at the amusement park, you strained a muscle in your neck. You are taking pain reliever that is 150 mg per tablet. The back of the bottle says you should not exceed 1.2 grams in 24 hours. How many tablets can you take to treat your pain in 1 day? (Note that 1 gram = 1000 mg)

People on a roller coaster
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First, we must make the units match: 1.2 g equation left hand side equals right hand side 1.2 multiplication 1000 mg equals 1200 mg. As 1200 division 150 equals eight, this indicates that you should not take more than 8 tablets of pain reliever in one day.

5.6.2 Self-Check on Negative Numbers