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Warm-Up

Warm-Up. True or False and Explain: 2/5% = 0.004% Exploration 6.5 (until 25 after). Exploration 6.5. Sales #1 - 4 Decrease and Increase #5 - 6 General formula?. Ways to estimate. A newspaper story reports that 8% of 7968 students work full time. Strategy 1: Use 10% as a benchmark

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Warm-Up

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  1. Warm-Up True or False and Explain: 2/5% = 0.004% Exploration 6.5 (until 25 after)

  2. Exploration 6.5 • Sales #1 - 4 • Decrease and Increase #5 - 6 • General formula?

  3. Ways to estimate • A newspaper story reports that 8% of 7968 students work full time. • Strategy 1: Use 10% as a benchmark • 10% of 7968 is 796.8, or about 797. • Strategy 2: Use 1% as a benchmark • 1% of 7968 is 79.68, or about 80. So 8% is 8 • 1%: 8 • 80 = 640.

  4. Ways to estimate • Strategy 3: find a close number: • 7968 is about 8000:10% of 8000 is 800; 8 • 1% is 8 • 80 = 640. • Strategy 4: find a range. • 8% is between 10% and 5%.5% of 8000 is 400. 10% of 8000 is 800. So 8% of 7968 is between 400 and 800.

  5. For exact answer: • Write and solve a proportion. Percent = part = is 100 whole of 8 = x --> 8 • 7968 = 100x 100 7968 63744 = 100x 637.44 = xAbout 637 students work full time.

  6. For most problems • Write the percent problem as a proportion; then solve.

  7. Example • My friend makes 68 baskets a week, and wants to sell no more than 30%. What is the maximum number of baskets she can sell?Part = Percent = Is Whole 100 Of • 30 = x --> 30 • 68 = 100x 100 68 • About 20.

  8. Try this on your own • My course coordinator’s son has 72 stuffed animals on his bed, but he generally only sleeps with 4 at a time. What percent of his animals does he sleep with? 4 = x --> 4 • 100 = 72x. X = 5.5%72 100

  9. Example • There is a 20% off sale at the mall. I’ve wanted this really cool sweater that is $120, but couldn’t afford it. How much less is the price with the sale? What is the sale price? • If the sale is 20% off, then the sweater is going to cost 100 - 20 = 80% of the original price. • New price: $96. Savings: $24. • Can you explain how to do this in your head?

  10. Example • The college bookstore makes a profit by charging students 25% more than the book actually cost wholesale. If your book cost $140, how much did the bookstore pay for it? • The bookstore pays 100%, and you pay 100 + 25 = 125%. • 100% = $x --> 100 • 140 = 125x125% $140

  11. Example • In the course of a year, there has been a decrease of 0.5% in the number of cacti in a certain zip code. If there had been about 640,000 cacti at the beginning of the year, how many are left now? • 100% in the beginning; 100 - 0.5 = 99.5% now.100 = 640,000 --> 100x = 99.5 • 640000 99.5 x About 636,800 cacti are left.

  12. Wednesday • Turn in the photocopy machine exploration (this is fun!) • See PP ahead of time to get idea of questions to ask. We will not have time to go through the whole thing. • Extra office hours will be announced

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