1. Ch. 7 Ratios and Proportions

2. Ch 7 Getting Started (p.287) Ratio Percent 48.1 77.5 7.4 2.9 1/5 2/3
19/23
3/5
39/50
8/25
3/50
9/10 24 40
5.5
3 1/3
6 ft
3 lb
1 ½ yd
195 min

3. 7-1 Ratios Fractions and in simplest form
Write each ratio as a fraction
25 to 10
6:18
8 to 56
27:15

4. 7-1 Ratios
Equivalent ratios have same value = should simplify to the same thing
Is each set equivalent? (prove with work)
6 to 8 and 36 to 48
9 to 2 and 45 to 6
3 to 8 and 6 to 12
35:5 and 14:2

5. 7-1 Ratios
It is recommended that no more than one person be allowed into the shallow end of an outdoor public pool for every 15 feet of surface area. If a local pool’s shallow end has a surface area of square feet, are the lifeguards correct to allow 120 people into that part of the pool?

6. 7-1 Ratios
p. 290 #15-31 odd
15. 1/ / / / / /8
27. yes both simplify to 3/5
29. yes both simplify to 8/21
31. yes both simplify to 4/3

7. 7-2 Rates Ratios with different labels
UNIT rates have a denominator of ONE
rate: 24 miles in 3 hours or 24 mi/3 hr
unit rate: 24 (÷3) = 8 mi or 8 mi/hr
3 (÷3) 1 hr

8. 7-2 Rates Make each ratio into a unit rate 228 feet in 24 seconds
$2 for six oranges
300 tickets in 6 days
220 miles on 8 gallons of gas

9. 7-2 Rates Best Buy (not the store)
the best option for buying an item is to get the one with the lowest unit rate
3 sizes of peanut butter, which is the best buy?
$2.49 for 12 oz.
$5.30 for 40 oz.
$10.89 for 80 oz.

10. 7-2 Rates Best Buy (not the store)
4 sizes of OJ, which is the best buy?
$1.28 for 16 oz.
$1.92 for 32 oz.
$2.56 for 64 oz.
$3.36 for 96 oz.

11. 7-2 Rates
p. 294 #10-17 all
mi.hr cust./day ppl/cls 13. $1.48/lb $0.14/oz cal/serv m/s mi/gal
oz bag aspirin
20. B it has 4.38 mg/oz instead of 5.83
21. 4,000 gal/min

12. 7-3 Solving Proportions proportions state that two ratios are equal
if two ratios are equal (proportional), then they have the same cross products
Are the ratios proportional?
6 = 3
$5 = $18
8oz oz

13. 7-3 Proportions
Check to see if each set of ratios can form a proportion
21 mi/6 hr and 14.3 mi/3 hr
$8/20 lb and $24/60 lb
27/6 and 9/2

14. 7-3 Proportions Solving Proportions
We can use proportions any time that we are comparing two similar things
Can use the complete information we know to fill in other missing information
Use cross products and basic equations to solve proportions

15. 7-3 Proportions
Cross Products to solve
5 = 10 x
2 = x

16. 7-3 Proportions
Cross Products to solve
6 = 3 x
3 = 760

17. 7-3 Proportions
The toy car shown below is modeled after a real car. If the real car is meters long, how wide is it?
6.6 cm
15.4 cm

18. 7-3 Proportions
An 8 oz. glass of orange juice contains 72 mg of vitamin C. How much juice contains 60 mg of vitamin C?
p. 300 #42-46

19. Review
p.300 #48-60

20. Quiz 3-D: Wednesday 2/1 write and simplify ratios (7-1)
calculate unit rates (7-2)
confirm proportions (7-3)
solve proportions (7-3)