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Objective 12/09/09. The students will be able to solve for the missing value in a proportion and solve word problems by using cross-products. A PowerPoint Presentation by Mrs. Mary Angel Alim- Flores. Proportions. Making Iced Tea. Making Iced Tea. Making Iced Tea. Making Iced Tea.
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Objective 12/09/09 The students will be able to solve for the missing value in a proportion and solve word problems by using cross-products.
A PowerPoint Presentation by Mrs. Mary Angel Alim- Flores Proportions
Two equal ratios form a PROPORTION. Ex. 5 : 10 = 20 : 40 56 = 7 64 8
2 Ways of Writing a Proportion 1. Colon Form 3:4 = 12: 16 2. Fraction Form 3 = 12 4 16
Extremes 16: 8 = 20:40 Means
To check if two ratios are equal or not: Fraction form • Use cross-products Ex. 3 = 15 4 20 (3x20=60) (4x15=60) Therefore, the two ratios form a proportion.
2. Colon form Check if the product of the means and product of the extremes are equal. Ex. 4: 6 _____ 12: 18 (6x12= 72) (18x4= 72) Therefore, the two ratios are equal.
To solve for the missing value. • Use cross products 5 = 60 10 x
5 = 6010 x 1st Step: 5(x)= 5x 2nd Step: 10 (60)= 600 3rd Step: 5x = 600 5 5 Answer: x= 120
12:36 = 3: m 1st Step: 12 (m)= 12m 2nd Step: 36 (3)= 108 3rd Step: 12m = 108 12 12 Answer: m= 9
Solving Word Problems Grace and James are on a swimming team. Their swim training is 200 meters and usually takes them 3 minutes. How long, at this rate, would it take them to complete an 800-meter swim?
1. Set up the proportion: meters200 = 800 minutes 3 n 2. Use cross-products 200(n)= 200 n then 3(800)= 2400. 3. Divide both sides by 200 n=12 Answer: 800-meter swim will take them 12 minutes.
A car travels 125 miles in 3 hours. How far would it travel in 5 hours?
A car travels 125 miles in 3 hours. How far would it travel in 5 hours? Step 1 Set up the proportion. miles 125 = h hours 3 5 Step 2 Solve for the missing value (h). 125(5) = 625 then, 3(h)=3h Step 3 Divide both 625 and 3h by 3 Answer: 208.33 or 208 1/3 miles
RECAP Today I learned… The steps in solving proportions are…
Trip Around the World • 1. U.S.A • 2. Philippines • 3. Australia • 4. Canada • 5. Japan
EXIT TICKET A 380- cubic cm sample of titanium has a mass of 1710 g. Find the weight of a titanium sample that has a volume of 532 cubic cm. Explain how you got your answer.