# COURSE 3 LESSON 5-4 Solving Proportions

## Presentation on theme: "COURSE 3 LESSON 5-4 Solving Proportions"— Presentation transcript:

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. , Test by writing as a proportion. 5 13 33 7 12 21 36 Write cross products. 5 • • 13 7 • • 21 Simplify. = / 252 = 252 5-4

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

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

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

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