Problem of the Day The last time you bought pizza, 3 pizzas were enough to feed 7 people. At that rate, how many pizzas should you buy for a party for 35 people? Find each unit cost and determine which item is the better buy. 5 towels for $39 or 7 towels for $46

Problem of the Day The last time you bought pizza, 3 pizzas were enough to feed 7 people. At that rate, how many pizzas should you buy for a party for 35 people? You should buy 15 pizzas. Find each unit cost and determine which item is the better buy. 5 towels for $39 or 7 towels for $46 $7.80 $6.57 The 7-towel price is the better buy.

A proportion is an equation stating that two ratios are equal. Proportions LESSON 5-3 What is Proportion A proportion is an equation stating that two ratios are equal. There are three ways to determine whether a pair of ratios form a proportion. Write in simplest form Find common multiplier between numerator and denominator Find cross-products and check for equality 5-3

Determine if the ratios can form a proportion. Proportions LESSON 5-3 Additional Examples Quick Check Determine if the ratios can form a proportion. 42 56 , 64 42 56 Divide 42 and 56 by their GCF, which is 14. = 3 4 42 56 ÷ 14 56 64 Divide 56 and 64 by their GCF, which is 8. = 7 8 56 64 ÷ 8 The ratios in simplest form are not equal. They cannot form a proportion. 5-3

 9  8  6 Determine if the ratios can form a proportion. , a. b. Proportions LESSON 5-3 Additional Examples Determine if the ratios can form a proportion. 2 3 18 24 , a. 5 4 30 b.  9  8  6 2 3 18 24 5 4 30 24 and cannot form a proportion. They don’t have a common multiplier. 2 3 18 24 and can form a proportion. 5 4 30 24 Quick Check 5-3

Determine if the ratios can form a proportion. Proportions LESSON 5-3 Additional Examples Determine if the ratios can form a proportion. 8 6 9 7 , b. a. 4 10 15 4 10 6 15 Test the pair of ratios. 8 6 9 7 4 • 15 10 • 6 Write cross products. 8 • 7 6 • 9 60 = 60 Simplify. 56 54 = / Yes, and form a proportion. 4 10 6 15 No, and do not form a proportion. 8 6 9 7 Quick Check 5-3

Determine if the ratios can form a proportion. 1. , 2. , 3. , 4. , Proportions LESSON 5-3 Lesson Quiz Determine if the ratios can form a proportion. 1. , 2. , 3. , 4. , 35 56 45 63 18 26 9 13 12 16 30 no yes yes no Now, start on the worksheet: Puzzle and Enrichment 5-3 5-3