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Download 7-9 Percent Problems Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day Lesson Quizzes Lesson Quizzes

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  • Slide 1
  • 7-9 Percent Problems Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day Lesson Quizzes Lesson Quizzes
  • Slide 2
  • 7-9 Percent Problems Warm Up Write each decimal as a percent and fraction. 1. 0.38 2. 0.06 3. 0.2 38%, 6%, 20%, 19 50 __ 3 50 __ 1 5
  • Slide 3
  • 7-9 Percent Problems Problem of the Day Lucky Jim won $16,000,000 in a lottery. Every year for 10 years he spent 50% of what was left. How much did Lucky Jim have after 10 years? $15,625
  • Slide 4
  • 7-9 Percent Problems Learn to find the missing value in a percent problem.
  • Slide 5
  • 7-9 Percent Problems To find the percent one number is of another, use this proportion: % 100 = is of Because you are looking for 45% of 420, 45 replaces the percent sign and 420 replaces of. The first denominator, 100, always stays the same. The is part is what you have been asked to find.
  • Slide 6
  • 7-9 Percent Problems Additional Example 1: Application First estimate your answer. Think: 35% =, which is close to, and 560 is close to 600. So about of the students participate in after-school sports. 35 100 ___ 1 3 __ 1 3 1 3 This is the estimate. 600 = 200 Think: 35 out of 100 is how many out of 560? Helpful Hint There are 560 students in Ellas school. If 35% of the students participate in after-school sports, how many students participate in after- school sports?
  • Slide 7
  • 7-9 Percent Problems Additional Example 1 Continued Now solve: s 560 ___ 35 100 ___ = 100 s = 35 560 100s = 19,600 100s 100 ____ 19,600 100 _____ = s = 196 Let s represent the number of students who participate in after- school sports. The cross products are equal. s is multiplied by 100. Divide both sides of the equation by 100 to undo multiplication. Since 196 is close to your estimate of 200, 196 is a reasonable answer. 196 students participate in after-school sports.
  • Slide 8
  • 7-9 Percent Problems Check It Out: Example 1 There are 480 students in Tishas school. If 70% of the students participate in the fundraising program, how many students participate in the fundraising program? First estimate your answer. Think: 70% =, which is close to, and 480 is close to 500. So about of the students participate in after school sports. 70 100 ___ 3 4 __ 3 4 This is the estimate. 3 4 __ 500 = 375
  • Slide 9
  • 7-9 Percent Problems Check It Out: Example 1 Continued Now solve: s 480 ___ 70 100 ___ = 100 s = 70 480 100s = 33,600 100s 100 ____ 33,600 100 _____ = s = 336 Let s represent the number of students who participate in the fundraising program. The cross products are equal. s is multiplied by 100. Divide both sides of the equation by 100 to undo multiplication. Since 336 is close to your estimate of 375, 336 is a reasonable answer. 336 students participate in the fundraising program.
  • Slide 10
  • 7-9 Percent Problems Additional Example 2: Application Johan is 25% of the way through his exercises. If he has exercised for 20 minutes so far, how much longer does he have to work out? is of __ % 100 ___ = 100 20 = 25 m 25% of the exercises are completed, so 20 minutes is 25% of the total time needed. The cross products are equal. 20 m __ 25 100 ___ = Set up a proportion. The of part is what you have been asked to find.
  • Slide 11
  • 7-9 Percent Problems Additional Example 2 Continued 2,000 = 25m 2,000 25 _____ 25m 25 ____ = 80 = m m is multiplied by 25. Divide both sides by 25 to undo multiplication. The time needed for the exercises is 80 min. So far, the exercises have taken 20 min. Because 80 20 = 60, Johan will be finished in 60 min.
  • Slide 12
  • 7-9 Percent Problems Check It Out: Example 2 Phil is 30% of the way through his homework. If he has worked for 15 minutes so far, how much longer does he have to work? is of __ % 100 ___ = 100 15 = 30 m 30% of the exercises are completed, so 15 minutes is 30% of the total time needed. The cross products are equal. 15 m __ 30 100 ___ = Set up a proportion. The of part is what you have been asked to find.
  • Slide 13
  • 7-9 Percent Problems Check It Out: Example 2 Continued 1,500 = 30m 1,500 30 _____ 30m 30 ____ = 50 = m m is multiplied by 30. Divide both sides by 30 to undo multiplication. The time needed for the homework is 50 min. So far, the homework has taken 15 min. Because 50 15 = 35, Phil will be finished in 35 min.
  • Slide 14
  • 7-9 Percent Problems Instead of using proportions, you can also multiply to find a percent of a number.
  • Slide 15
  • 7-9 Percent Problems Additional Example 3: Multiplying to Find a Percent of a Number 36% = 0.36 0.36 50 Write the percent as a decimal. Multiply using the decimal. 18 So 18 is 36% of 50. Find 36% of 50. 0 5 10 15 20 25 30 35 40 45 50 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Check Use a model to check the answer.
  • Slide 16
  • 7-9 Percent Problems Check It Out: Example 3 20% = 0.20 0.20 70 Write the percent as a decimal. Multiply using the decimal. 14 So 14 is 20% of 70. Find 20% of 70. 0 7 14 21 28 35 42 49 56 63 70 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Check Use a model to check the answer.
  • Slide 17
  • 7-9 Percent Problems Standard Lesson Quiz Lesson Quizzes Lesson Quiz for Student Response Systems
  • Slide 18
  • 7-9 Percent Problems Lesson Quiz 1. Find 28% of 310. 2. Find 70% of 542. 3. Martha is taking a 100-question test. She has completed 60% of the test in 45 minutes. How much longer will it take her to finish the test? 4. Crystal has a collection of 72 pennies. If 25% of them are Canadian, how many Canadian pennies does she have? 379.4 86.8 30 min 18
  • Slide 19
  • 7-9 Percent Problems 1. Identify 35% of 260. A. 35 B. 91 C. 260 D. 295 Lesson Quiz for Student Response Systems
  • Slide 20
  • 7-9 Percent Problems 2. Identify 60% of 422. A. 253.2 B. 482 C. 362 D. 25320 Lesson Quiz for Student Response Systems
  • Slide 21
  • 7-9 Percent Problems 3. Ella has to draw a flowchart as a part of an assignment. She has drawn 40% of the flowchart in 10 minutes. How much longer will it take her to complete the flowchart? A. 10 min B. 25 min C. 15 min D. 35 min Lesson Quiz for Student Response Systems
  • Slide 22
  • 7-9 Percent Problems 4. Of 80 sheep in a field, 65% are ewes. How many ewes are there in the field? A. 28 ewes B. 52 ewes C. 65 ewes D. 108 ewes Lesson Quiz for Student Response Systems

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