Ratios, Proportions, and Percents

Ratios A ratio compares two quantities. A ratio can be written in three ways. Write ratios in their simplest form. The number of hearts (5) to lightning bolts (4) can be written 5:4, 5 to 4, or 5/4. The ratio of stars (6) to lightning bolts (4) needs to be simplified. It can be written 3:2, 3 to 2, or 3/2. Write the ratio of hearts to total objects in three ways.

Ratios A ratio compares two quantities. A ratio can be written in three ways. Write ratios in their simplest form. The number of hearts (5) to lightning bolts (4) can be written 5:4, 5 to 4, or 5/4. The ratio of stars (6) to lightning bolts (4) needs to be simplified. It can be written 3:2, 3 to 2, or 3/2. Write the ratio of hearts to total objects in three ways. 1:3, 1 to 3, 1/3

the cross products are equal Proportions A proportion is a statement that two ratios are equivalent. Two ratios form a proportion if: the cross products are equal the units are the same 5×16 and 4×20 are cross products. Each ratio compares hearts to lightning bolts. The cross products are equal.

Use Proportions to Solve Problems Step 1: Let n equal the unknown quantity. Step 2: Set up a proportion. Step 3: Use cross products to solve. Problem: Jenna can buy 150 cell phone minutes for $12. What will she pay for 225 cell phone minutes? Step 1: Let n equal the cost for 225 minutes. Step 3: 150 × n = 12 × 225 150n = 2700 = Step 2: n = 18 Jenna will pay $18 for 225 minutes.

Use Proportions to Solve Problems Step 1: Let n equal the unknown quantity. Step 2: Set up a proportion. Step 3: Use cross products to solve. Use a proportion to solve. Show your work. Adam rode his bicycle 105 miles in 3 hours. How many miles did he ride in 2 hours?

Use Proportions to Solve Problems Step 1: Let n equal the unknown quantity. Step 2: Set up a proportion. Step 3: Use cross products to solve. Use a proportion to solve. Show your work. Adam rode his bicycle 105 miles in 3 hours. How many miles did he ride in 2 hours? 105 miles 2 hours n miles 3 hours = 3 × n = 105 × 2 3n = 210 3n 3 210 n = 70

You can use a proportion to solve percent problems. Percents A percent is a ratio in which the first term of the ratio is compared to 100. You can use a proportion to solve percent problems. Example: 7% = 7 to 100, 7:100, or 7/100 What is 35% of 80? 35% of 80 is 28. What is 12% of 125? 36 is 45% of what number? 15 is what percent of 75?

You can use a proportion to solve percent problems. Percents A percent is a ratio in which the first term of the ratio is compared to 100. You can use a proportion to solve percent problems. Example: 7% = 7 to 100, 7:100, or 7/100 What is 35% of 80? 35% of 80 is 28. What is 12% of 125? 36 is 45% of what number? 15 is what percent of 75? 15 80 20%

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