Solve Proportional Relationships
CROSS PRODUCT RULE In the proportion =, the cross products, a · d and b · c are equal. abab cdcd EX 1) = uses 1. Prove proportionality EX 2) = Disprove proportionality 3. Compare fractions EX 3) < <
Use the cross products to solve proportions with variables. Which help you find missing values. m = 3 Set up proportion. Cross Multiply. Divide by 15 = m5m EX 4) Step 1 Step 2 Step 3 9 x 5= ÷ 15
Unit rate : a rate whose denominator is 1. It may not always look like a number; watch for words like per or each. miles EX 5) 200/ 4hours How many miles traveled per hour? Step 2: set up proportion = Step 1: highlight rates Miles HoursHour X 1 Step 3: Cross multiply and divide 200 X 1 = 200 ÷ 4= 50 X = 50 mph
The ratio of students who ordered pizza to those that did not order pizza was 5 : 3. How many students would have pizza if 24 students ordered. EX 6) += not ordered ordered Total ordered = pizza X total X = 15
Sue needs 9 cups of flour to make 16 batches of cookies. How much flour does she need if she only wants to make a fourth of her recipe. = cups Cups 9 16 X X batches 4 9 X 4 = ÷ 16 = = Cups EX 7)
A 12 oz sport drink cost $1.08 and a 16 oz. sport drink cost $1.28. Which drink is the better buy? Step 2: set up proportion = Step 1: highlight rates oz $ $ X 1 Step 3: Cross multiply and divide EX 8) Since you are comparing you will set up two proportions = oz $ X 1 $ X = 0.09 X = 0.08 The 16 oz. sport drink is the better buy?
Essential Question How do you solve proportions?
Date _____________ Solve Proportional Relationships
CROSS PRODUCT RULE In the proportion =, the cross products, a · d and b · c are equal. abab cdcd EX 1) uses 1. EX 2) EX 3)
You can use the cross product rule to solve proportions with variables. Which help you find missing values. = = = EX 4)
How many miles traveled per hour? miles Unit rate : a rate whose denominator is 1. It may not always look like a number; watch for words like per or each. EX 5) / hours Step 2: = Step 1: Step 3:
The ratio of students who ordered pizza to those that did not order pizza was :. How many students would have pizza if students ordered. EX 6) += =
Sue needs cups of flour to make batches of cookies. How much flour does she need if she only wants to make a fourth of her recipe. = EX 7)
A 12 oz sport drink cost $1.08 and a 16 oz. sport drink cost $1.28. Which drink is the better buy? = EX 8) =
Essential Question How do you solve proportions?