1150 day 11
- 2. A ratio is a comparison of two quantities. Write a ratio comparing the number of squares to the number of circles. 3 to 2 3:2 3 2
- 3. Two equal ratios form a proportion. Circles 2 4 squares 3 6 2=4 3 6 proportion
- 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
- 6. Three out of every 10 adults segregate their food. a) Write this information as a ratio. Segregators 3 total 10 b) In a group of 90 people, how many would you expect to be food segregators? x9 Segregators 3 = x x = 27 total 10 90 x9
- 7. The scale on a map is 1 inch = 20 miles. a) If two towns are 4 ½ inches apart on the map, how many miles apart are they? 1x 20 · 4 ½ x = 20 · 9 = 180 = 90 Inch 1 = 4½ 2 2 Mile 20 x 90 miles apart b) If two towns are 75 miles apart, how far apart will they be on the map? 75 20x 20x = 75 3 ¾ inches apart Inch 1 = x 20 20 Mile 20 75 x = 75 5 = 15 20 5 4
- 8. 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
- 9. Fractions/Decimals/Percents Percents Fractions 16 4 16% = 100 25 Move decimal point Percents Decimals two places left 16 16% = = 0.16 175% = 1.75 100 0.05% = 0.0005
- 10. 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
- 11. Decimals Percents Move decimal point two places right 37 0.37 = 37% 100 0.0004 = 0.04% 36.7 = 3670%
- 12. The Percent Proportion percent part = 100 whole What is 20% of 18? 20 x 100x = 360 = 100 100 100 18 x = 3.6
- 13. 3 is 6% of what number? part percent whole percent part = 100 whole 6 3 = 100 x 6x = 300 6 6 x = 50
- 14. A dress that normally sells for $80 is on sale for $52. What is the “percent off”? 1) Find the markdown 80 – 52 = 28 2) Percent: x Part: 28 Whole: 80 x 28 = 100 80 80x = 2800 x = 35 35 % off