Proportions and Cross Multiply

Determine whether each pair of ratios forms a proportion

• Proportion

• Not a Proportion

A 12-ounce bottle of shampoo lasts Enrique 16 weeks. How long would you expect an 18-ounce bottle of the same brand to last him?

• 24 Weeks

• 24-ounce bottle

• 10.6 Weeks

• 10.6-ounce bottle

The distance that an automobile travels varies directly as the time it travels. If the car travels 280 miles in 7 hours, how far will it travel in 12 hours?

• 480

• 1960

• 84

• 25

What is the new equation after you cross multiply?

• 25x

• 4/25

What is the value of x ?

• x = 25/4

• x = 25

• x = 4/25

• x = 4

What is NOT a correct way to find the missing number?

• Check for a multiplication or division relationship

• Use Cross Products (cross multiply)

• Divide the top and bottom by the same number to simplify 3/12

• Typing the two fractions into the calculator and letting it do the math

What is the missing number for this proportion?

• 1

• 3

• 9

Using your equation from before, what is q ?

• q = 2

• q = 9

• q = 9/2

• q = 2/9

• Multiply both sides by 4

• Divide both sides by 25

• Divide both sides by 4

What is the ratio of apples to bananas?