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Holt CA Course 1 6-5 Solving Percents Problems NS1.4 Calculate given percentages of quantities and solve problems involving discounts at sales, interest.

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Presentation on theme: "Holt CA Course 1 6-5 Solving Percents Problems NS1.4 Calculate given percentages of quantities and solve problems involving discounts at sales, interest."— Presentation transcript:

1 Holt CA Course Solving Percents Problems NS1.4 Calculate given percentages of quantities and solve problems involving discounts at sales, interest earned, and tips. Also covered: NS1.3, AF1.1 California Standards

2 Holt CA Course Solving Percents Problems Sloths sleep an average of 16.5 hours a day. To find out what percent of a 24-hour day 16.5 hours is, you can use a proportion or an equation.

3 Holt CA Course Solving Percents Problems Proportion Method Equation Method n 100 = Part Whole Part Whole What percent of 24 is 16.5? n · 24 = 100 · n = 1,650 n = n · 24 = 16.5 n = n = 68.75% Sloths spend about 69% of the day sleeping!

4 Holt CA Course Solving Percents Problems Solve. Additional Example 1: Using Proportions to Solve Problems with Percents A. What percent of 40 is 25? n 100 = n · 40 = 100 · 25 40n = 2,500 40n 40 = 2, n = is 62.5% of 40. Write a proportion. Set the cross products equal. Multiply. Divide each side by 40.

5 Holt CA Course Solving Percents Problems Solve. Additional Example 1: Using Proportions to Solve Problems with Percents B. 15 is 25% of what number? = 15 n n · 25 = 100 · 15 25n = 1,500 25n 25 = 1, n = is 25% of 60. Write a proportion. Set the cross products equal. Multiply. Divide each side by 25.

6 Holt CA Course Solving Percents Problems Solve. Check It Out! Example 1 A. What percent of 50 is 10? n 100 = n · 50 = 100 · 10 50n = 1,000 50n 50 = 1, n = is 20% of 50. Write a proportion. Set the cross products equal. Multiply. Divide each side by 50.

7 Holt CA Course Solving Percents Problems Solve. Check It Out! Example 1 B. 8 is 40% of what number? = 8n8n n · 40 = 100 · 8 40n = n 40 = n = 20 8 is 40% of 20. Write a proportion. Set the cross products equal. Multiply. Divide each side by 40.

8 Holt CA Course Solving Percents Problems Solve. Additional Example 2: Using Equations to Solve Problems with Percents A. 35 is 28% of what number? 35 = 28% · n 35 = 0.28 · n = 0.28 · n = n 35 is 28% of 125. Write an equation. Write 28% as a decimal. Divide each side by 0.28.

9 Holt CA Course Solving Percents Problems Solve. Additional Example 2: Using Equations to Solve Problems with Percents B. What percent of 9 is 18? 18 = n · = n · = n 200% = n 18 is 200% of 9. Write an equation. Divide each side by 9. Write the decimal as a percent.

10 Holt CA Course Solving Percents Problems Solve. Check It Out! Example 2 A. 36 is 24% of what number? 36 = 24% · n 36 = 0.24 · n 150 = n 36 is 24% of 150. Write an equation. Write 24% as a decimal. Divide each side by = 0.24 · n 0.24

11 Holt CA Course Solving Percents Problems Solve. Check It Out! Example 2 B. What percent of 6 is 36? 36 = n · = n · = n 600% = n 36 is 600% of 6. Write an equation. Divide each side by 6. Write the decimal as a percent.

12 Holt CA Course Solving Percents Problems A portable DVD player costs $225 before tax at an appliance warehouse. What is the sales tax rate if the tax is $18? Additional Example 3: Finding Sales Tax n 100 = n · 225 = 100 · 18 8% of $225 is $18. The sales tax is 8%. Write a proportion. Set the cross products equal. Multiply. Restate the question: What percent of $225 is $18? 225n = n 225 = Divide each side by 225. n = 8

13 Holt CA Course Solving Percents Problems Helpful Hint The sales tax rate is the percent used to calculate sales tax.

14 Holt CA Course Solving Percents Problems A new flat screen TV costs $800 before tax at an appliance warehouse. What is the sales tax rate if the tax is $56? Check It Out! Example 3 n 100 = n · 800 = 100 · 56 7% of $800 is $56. The sales tax is 7%. Write a proportion. Set the cross products equal. Multiply. Restate the question: What percent of $800 is $56? 800n = n 800 = Divide each side by 800. n = 7


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