Setting Up and Solving Proportions!

Set Up the proportion and solve! If 12 bananas weigh 3lbs, how many bananas would weigh 15 lbs?

Multiply 15 times 12 and then divide by 3. First set it up Then Use cross products to solve Multiply 15 times 12 and then divide by 3. If there is a shortcut go ahead and use it!

Cross products Short cut 12 x 15= 180 180÷3 = 60 60 bananas Since 3 goes into 15 five times, just multiply both the top and bottom number by 5. 12 x 5 = 60 60 bananas

Solving with Algebra Another way 12 x 15 = 3x 180 = 3x 3 3 60 = x 12 x 15 = 3x 180 = 3x 180 ÷ 3 = 3x ÷ 3 60 = x

Set Up the proportion and solve! If 12 bananas weigh 3lbs, how much would 156 bananas weigh?

If 12 bananas weigh 3lbs, how much would 156 bananas weigh? Multiple ways to set up proportion If 12 bananas weigh 3lbs, how much would 156 bananas weigh?

You multiply the same numbers any way you set it up! Multiple ways to set up proportion You multiply the same numbers any way you set it up!

156 x 3 = 12x 468 = 12x 12 12 39 = x 156 bananas would weigh 39 lbs. Solving with algebra 156 x 3 = 12x 468 = 12x 12 12 39 = x 156 bananas would weigh 39 lbs. 156 x 3 = 12x 468 = 12x 468 ÷ 12= 12x ÷ 12 39 = x

New type of problem. If I can get 2 lbs of chocolate stars for $6, how much would it cost for 3 lbs?

It is pretty easy to solve using cross products, but there is also a relationship between the numerator and denominator. Use this shortcut when you can! 2 x 3 equals 6, so 3 x 3= 9 The answer is $9

The answers are not always going to be whole numbers! Different type of problem. If I can get 4 lbs of chocolate stars for $6, how much would it cost for 3 lbs? The answers are not always going to be whole numbers! 18 ÷ 4 = $4.50

If a group can wash 10 cars in 12 minutes at a fundraiser, how many cars can be washed in 18 minutes?

Can you figure it out an easier way? If a group can wash 10 cars in 12 minutes at a fundraiser, how many cars can be washed in 18 minutes? If you simplify the ratio, then there is an easy shortcut!

Using simplifying shortcut 6 x 3 = 18 so 5 x 3 = 15 15 cars can be washed in 18 minutes

A little tougher now! If I can grade 25 warmups in 2 hours, how many warmups can I grade in 5 hours? (Round to the nearest paper)

The answer is?????? 62.5 which rounds to 63!

You can do it!!!!! My Roundup weed killer says to mix 4 fl oz of concentrate for each 128 fl oz of water. If I have a spray bottle that holds 40 fluid oz of water, how much Roundup concentrate should I add?

And the answer is ????? 4 x 40 = 128 x 160 = 128x 160 ÷ 128 = 128x ÷ 128 1.25 = x The answer is 1.25 or 1¼ fl. oz. concentrate

What Questions do you still have?