Lesson 16 Solving Problems With Measures
Example 1 Jeff cut a string 4 feet long into three equal pieces. How long are the pieces? Strategy: Change to another unit if necessary. Step 1: Decide what operation will solve the problem. Use division, since you have to divide the string.
Step 2: Notice that you cannot divide 4 feet by 3 evenly. If the string were 3 feet or 6 feet long, then you could divide the number evenly by 3 (it may be ok to have a mixed number for an answer). Step 3: Use the Customary Measurement table, if you don’t know the conversion factor, found in Lesson 29, the back of your text, or in your planner, to convert feet to inches. 1 foot = 12 inches so 4 feet = 4 x 12 = 48 inches.
Step 4: Divide the number of inches by inches / 3 = 16 inches.
Solution Each piece of string is 16 inches long (or 1 foot 4 inches long). It can also be 1 1/3 feet long.
Example 2 Manny brought 8 packages to the post office. Each weighed 3 pounds 7 ounces. How much did the packages weigh all together? Strategy: Use the conversion tables if necessary.
Step 1: Decide what operation will solve the problem. Use multiplication, since you want to find the total weight. Step 2: Do the math – multiply pounds and ounces separately. 3 lb. X 8 = 24 lb.; 7 oz. X 8 = 56 oz. Step 3: Use the Customary Measurement conversion table to convert ounces to pounds if you do not know the conversion factor. 16 oz. = 1 lb. So, 56 oz. / 16 = 3 lb. 8 oz.
Step 4 Add the pounds together from Steps 2 and lb. + 3lb. = 27 lb. Step 5: Add the ounces.
Solution The packages weighed 27 lb. 8 oz. Tip: Converting to the smaller unit of measure will make solving the problem easier.
Example 3 The temperature outside of Clara’s classroom on Monday at noon is 15 C. The next morning the temperature went down 18 degrees. What was the temperature the next day? Strategy: Subtract 18 degrees or add - 18 degrees. Use a number line if you need to show the problem.
Step 1: 15 – 18 = or 15 + (-18) = -3
Solution The temperature was -3 or 3 below 0 the next day.