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Warm-up

Warm-up. Learn to estimate with percents. Going to get into groups of 3 Work together on wkbk pg. 68 #1-5 Come up with a strategy for estimating Each group will share their strategy for the problem I choose for them . You will have about 20 minutes. 12 24. 13 24. . not compatible.

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Warm-up

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  1. Warm-up

  2. Learn to estimate with percents.

  3. Going to get into groups of 3 • Work together on wkbk pg. 68 #1-5 • Come up with a strategy for estimating • Each group will share their strategy for the problem I choose for them. • You will have about 20 minutes.

  4. 12 24 13 24  not compatible compatible Some problems require only an estimate. Estimates involving percents and fractions can be found by using compatible numbers, numbers that go well together because they have common factors.

  5. 1 1 21 20  65 = 13 Use mental math: 65 ÷ 5. 5 5 100 100 Estimate. A. 21% of 66 Instead of computing the exact answer of 21%  66, estimate. Use compatible numbers, 20 and 100. 21% =  Simplify. 66  65 Use compatible numbers, 65 and 5. So 21% of 66 is about 13.

  6. Estimate. B. 36% of 120 Instead of computing the exact answer of 36%  120, estimate. 36%  35% Round.  30% + 5% Break down the percent into smaller parts.  3  10% + 5% 35%  120 = (3  10% + 5%)  120 Set up an equation.

  7. Additional Example 1B Continued = 3  10%  120 + 5% 120 Use Distributive Property. = 36 + 6 10% of 120 is 12, so 5% of 120 is 6. = 42 So 36% of 120 is about 42.

  8. 3 3 29 30  90 = 27 Use mental math: 90 ÷ 10. 10 10 100 100 Try This: Example 1A Estimate. A. 29% of 86 Instead of computing the exact answer of 29%  86, estimate. Use compatible numbers, 30 and 100. 29% =  Simplify. 86  90 Use compatible numbers, 90 and 10. So 29% of 86 is about 27.

  9. Try This: Example 1B Estimate. B. 44% of 130 Instead of computing the exact answer of 44%  130, estimate. 44%  45% Round.  40% + 5% Break down the percent into smaller parts.  4  10% + 5% 45%  130 = (4  10% + 5%)  130 Set up an equation.

  10. Try This: Example 1B Continued = 4  10%  130 + 5% 130 Setup an equation. = 42 + 6.5 10% of 130 is 13, so 5% of 130 is 6.5. = 48.5 So 44% of 130 is about 48.5.

  11. The diameter of the Moon is about 2160 miles. If the diameter of the Moon is about 27% of the diameter of Earth, what is the approximate diameter of Earth?

  12. 1 Diameter of the Moon  27%  Diameter of Earth Understand the Problem Additional Example 2 Continued The answer is the approximate diameter of Earth. List the important information: • The diameter of the Moon is about 2160 miles. • The diameter of the Moon is about 27% of the diameter of the Earth. Let e represent the diameter of the Earth. 2160  27% e

  13. Make a Plan 25 100 25% = = 1 4 2 Think: The numbers 2160 and 27% are difficult to work with. Use compatible numbers: 2160 is close to 2000; 27% is close to 25% Find an equivalent ratio for 25%.

  14. 3 Solve Think: 2000 is of what number? 1 4 Additional Example 2 Continued 4  2000 = e 8000 = e The diameter of Earth is approximately 8000 miles.

  15. 25% of 8000 mi is , or 2000 mi. This is the approximate diameter of the moon. 8000 4 4 Look Back

  16. Lesson Quiz Estimate. 1. 34% of 12 2. 47 out of 236 3. 113% of 80 4. 22 out of 51 5. According to the last census, 33,871,648 people live in California, and 3,694,820 of those people live in Los Angeles. Estimate the percent of Californians who live in Los Angeles. Possible answers: 4 20% 90 40% 10%

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