5.1.2 Weight Measurements

[ The ounce was originally based on the weight of that very useful item, the barleycorn, with 480 barleycorns to the ounce (although it couldn't have been much fun counting 480 of them). Having 16 ounces to the pound was useful because 16 can be divided into halves (8, 4, 2, 1) very easily. ] To measure weight, ounces (abbreviated oz) and pounds (abbreviated lbs) are used. Once again, the relationship between these units may seem random; there are 16 ounces in one pound.

Let’s suppose you were moving boxes of electronic equipment. The first box weighs 14 pounds 11 ounces. The second one weighs 17 pounds 8 ounces. What is the total weight of both boxes?

First, we can add the pounds together: 14 pounds prefix plus of 17 pounds equals 31 pounds.

Next we add up the ounces: 11 ounces prefix plus of eight ounces equals 19 ounces. Since there are 16 ounces in 1 pound, this means 19 ounces equals 16 ounces prefix plus of three ounces equals one pound prefix plus of three ounces.

Thus, we have a total of 31 pounds prefix plus of one pound prefix plus of three ounces equals 32 pounds prefix plus of three ounces. The boxes weigh a total of 32 pounds 3 ounces.

Activity symbol Activity: Weight

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

(a) At birth, Samuel weighs 7 pounds 4 ounces. After one week, he has gained 13 ounces. How much does Samuel weigh now in pounds and ounces?

Hint symbol

Discussion

Gaining weight would require addition. Losing weight would indicate the need to subtract. Multiplication is used to carry out repeated addition.

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Answer

(a) multiline equation line 1 seven pounds four ounces line 2 prefix plus of 13 ounces divided by seven pounds 17 ounces

However, since there are 16 ounces in 1 pound then 17 ounces equals 16 ounces prefix plus of one ounce equals one pound prefix plus of one ounce, the correct way to say this is that Samuel now weighs 8 pounds 1 ounce.

(b) When she started dieting, Beth weighed 203 pounds. She lost 37 pounds. How much does Beth now weigh?

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Answer

(b) Beth now weighs 203 pounds negative 37 pounds equals 166 pounds.

(c) A recipe for a meal for one person requires 3 ounces of meat. How much meat would be needed to feed a party of 14 people? Give your answer in pounds and ounces.

Solution symbol

Answer

(c) The recipe calls for a total of three ounces prefix multiplication of 14 equals 42 ounces.

Because 42 division 16 equals two cap r 10, this indicates that there would need to be 2 pounds 10 ounces of meat purchased for the party.

5.1.1 Length Measurements

5.1.3 Volume Measurements