Use unit analysis to convert 3 days to seconds. Solution We are given days and want to convert to seconds. The relationships are 1 day 24 hr 1 hr 60 min 1 min 60 sec We will do this conversion in a single step using more than one unit fraction. Use this unit fraction to change hours to minutes. 3 days 1 24 hr 1 day ⎧⎨⎩ 60 min 1 hr 60 sec 1 min Divide out the correct units. ⎧⎨⎩ Use this unit fraction to change days to hours. ⎧⎨⎩ Finally, use this unit fraction to change minutes to seconds. 259,200 sec 1 259,200 sec Multiply and simplify. Therefore, 3 days 259,200 sec. EXAMPLE 6 YOU TRY 6 Use unit analysis to convert 3 gal to cups. 4 Solve Applied Problems Using Unit Analysis Unit analysis can be used to solve many different types of applied problems. Larry is a chef, and his company is catering a large party. One batch of cheese fondue uses 3 4 cup heavy cream. If he needs to make 12 times that amount of cheese fondue, how many quarts of heavy cream does he need? Solution Let’s restate the problem in our own words to be sure we understand it. One batch of cheese fondue uses 3 4 c heavy cream. We must determine the number of quarts of heavy cream needed to make 12 batches of fondue. To solve the problem, fi rst multiply 3 4 c by 12 to determine the number of cups of heavy cream needed. Then, change the number of cups to quarts. Total cups of heavy cream needed: 3 4 c 12 3 4 c 12 1 9 c EXAMPLE 7 www.mhhe.com/messersmith SECTION 7.1 Using U.S. Customary Measurements 573
messersmith_power_prealgebra_1e_ch4_7_10
To see the actual publication please follow the link above