1150 day 11

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1150 day 11

  1. 1. Ratios, Proportionsand Percents
  2. 2. A ratio is a comparison of two quantities.Write a ratio comparing the number of squares tothe number of circles. 3 to 2 3:2 3 2
  3. 3. Two equal ratios form a proportion. Circles 2 4 squares 3 6 2=4 3 6 proportion
  4. 4. Solving proportions x3 3= n n=9 Look for a multiplier 4 12 (scale factor) x3 30 7n No obvious multiplier - 5= n Cross multiply 7 6 7n = 30 7 7 2 n=47
  5. 5. Three out of every 10 adults segregate their food.a) Write this information as a ratio. Segregators 3 total 10b) In a group of 90 people, how many would you expect to be food segregators? x9Segregators 3 = x x = 27 total 10 90 x9
  6. 6. The scale on a map is 1 inch = 20 miles.a) If two towns are 4 ½ inches apart on the map, howmany miles apart are they? 1x 20 · 4 ½ x = 20 · 9 = 180 = 90Inch 1 = 4½ 2 2Mile 20 x 90 miles apartb) If two towns are 75 miles apart, how far apart willthey be on the map? 75 20x 20x = 75 3 ¾ inches apartInch 1 = x 20 20Mile 20 75 x = 75 5 = 15 20 5 4
  7. 7. Percents• “Percent” means “out of 100”• Percents are rational numbers 41 41% = 100 260 260% = 100 0.2 10 2 0.2% = 100 10 1000 100 1 100% = 100
  8. 8. Fractions/Decimals/PercentsPercents Fractions 16 416% = 100 25 Move decimal pointPercents Decimals two places left 1616% = = 0.16 175% = 1.75 100 0.05% = 0.0005
  9. 9. Fractions Percents 5 x5 25 = 25% 20 x5 100 16 3 50 6x = 100 3 1 x 6 6 20 6 100 x = 50 18 3 2 2 = 16 % 3
  10. 10. Decimals Percents Move decimal point two places right 370.37 = 37% 100 0.0004 = 0.04% 36.7 = 3670%
  11. 11. The Percent Proportion percent part = 100 whole What is 20% of 18? 20 x 100x = 360 = 100 100 100 18 x = 3.6
  12. 12. 3 is 6% of what number?part percent whole percent part = 100 whole 6 3 = 100 x 6x = 300 6 6 x = 50
  13. 13. A dress that normally sells for $80 is on sale for $52.What is the “percent off”?1) Find the markdown 80 – 52 = 282) Percent: x Part: 28 Whole: 80 x 28 = 100 80 80x = 2800 x = 35 35 % off

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