Solving Proportions

1. = / 5 13 13 33 Test by writing as a proportion. 7 12 21 36 Write cross products. 7 • 36 12 • 21 5 • 33 13 • 13 Simplify. 165 169 252 = 252 COURSE 3 LESSON 5-4 Solving Proportions Use cross products to determine whether the ratios form a proportion. 5 13 13 33 7 12 21 36 a. , b. , 5-4

2. 5p = 32 • 10 Write the cross products. 5p = 320 Multiply. 5p 5 320 5 = Divide each side by 5. Simplify. p = 64 COURSE 3 LESSON 5-4 Solving Proportions Solve each proportion. 5 32 10 p a. = 5-4

3. 3 5 q 54 b. = 1 2 1 2 3 5 Estimate The ratio is close to , so q is about of 54, or 27. Write the cross products. 3 • 54 = 5q 162 = 5q Multiply. 162p 5 5q 5 Divide each side by 5. = 32.4 = q Simplify. COURSE 3 LESSON 5-4 Solving Proportions (continued) Check for Reasonableness The answer 32.4 is close to the estimate 27. The answer is reasonable. 5-4

4. 0.7876 1 125 p Write the proportion . = Irish pounds euros Write the cross products. 0.7876 • p = 1 • 125 0.7876 • p 0.7876 125 0.7876 Divide each side by 0.7876. = Use a calculator. 125 0.7876 158.710005 COURSE 3 LESSON 5-4 Solving Proportions The fixed rate of conversion is 1 euro = 0.7876 Irish pounds. How many euros would you receive for 125 Irish pounds? Let p = the number of euros. You would receive 158.71 euros. 5-4

5. Solve each proportion. 1. = 2. = 3. Suppose the exchange rate for dollars to Indian rupees is 0.02. How many rupees should you receive for $100? w 12 3 4 4 5 20 r COURSE 3 LESSON 5-4 Solving Proportions 9 25 5,000 rupees 5-4