Page 90

messersmith_power_prealgebra_1e_ch4_7_10

Note We could have changed the units in the unit cost of Brand B from $22.59/lb to dollars/oz so that the units matched those of Brand A. YOU TRY 8 Sonja has to buy basil leaves at the grocery store. The label on the shelf for Brand A says that its unit cost is $3.59/oz. The label for Brand B says that the unit cost is $49.89/lb. Which is the better buy? ANSWERS TO YOU TRY EXERCISES 1) a) 3 b) 2000 c) 2 2) a) 4 tons b) 3 pt c) 7.1 Exercises Do the exercises, and check your work. Objective 1: Learn U.S. Customary Measurements In U.S. customary units, 1) name three units used to measure length. 2) name three units used to measure capacity. 3) what is the relationship between inches and feet? 4) what is the relationship between ounces and pounds? Fill in the blank. 5) 1 min sec; min 1 hr 6) 1 day hr; sec 1 min 7) ft 1 yd; ft 1 mi 8) fl oz 1 c; 1 pt c 9) pt 1 qt; 1 c fl oz 10) 1 ton lb; oz 1 lb Objective 2: Use Multiplication or Division to Convert Between Units In U.S. customary units, 11) when do you use division to convert between units? 12) when do you use multiplication to convert between units? 1 5 min d) 13.5 ft 3) 2 hr 4) a) 48 oz b) 4 1 2 pt or 4.5 pt c) 4 5 hr or 0.8 hr d) 11,880 ft 5) 1 3 hr 6) 48 c 7) 1 qt 8) Brand B is the better buy because the unit cost of Brand A is $57.44/lb. Using Technology When using more than one unit fraction to convert to a desired unit, we can use a calculator to perform the required calculation. Suppose we wanted to convert 100 c to gallons. In this case, our expression of unit fractions would be 100 c 1 pt 1 qt 1 gal . 1 2 c 2 pt 4 qt (Note: Because dividing or multiplying by 1 does not affect the fi nal answer, we can disregard them in the calculation.) To perform the calculation with a calculator (disregarding the 1’s) we enter 1 0 0 2 2 4 . The display will likely show 6.25. This means 100 c 6.25 gal. It is a common mistake to enter 1 0 0 2 2 4 into the calculator for this problem. Why is this incorrect? www.mhhe.com/messersmith SECTION 7.1 Using U.S. Customary Measurements 575


messersmith_power_prealgebra_1e_ch4_7_10
To see the actual publication please follow the link above