1. Ratio and Proportion
Ms. Crusenberry
9-2013

2. Vocabulary Ratio – comparison of two numbers using division
Comparison – examining two numbers to see which is larger
Fractional Form – expressed as a fraction

3. A Ratio as a Fraction
Example: 9 to = 4 **always simplify

4. Practice
12 to 20
18 to 21
8 to 19
125 to 250

5. Answers
3/5
6/7
8/19
1/2

6. Writing a Ratio from Words
Example: 15 minutes to 1 hour to 60 = 5 to /60 = 5/12

7. Practice 150 miles to 4 hours 4 hits for 6 times at bat
1 year to 8 months
1 fifty-cent piece to 1 dime

8. Answers
75/2
2/3
3/2
5/1

9. Identifying Proportions
A proportion is two equal ratios Example: **cross multiply first numerator by the second denominator and put that answer on the left side – then multiply the first denominator by the second numerator and put that answer on the right side. If they equal, then they are proportionate.

10. Practice
10/16 5/8
4/8 2/3
5/9 15/27
**1 1/2/3 3/6

11. Answers =

12. Solving Proportions
Example: = n Cross multiply to get: = 4n Divide each side by = n

13. Practice
12/n = 20/25
2/3 = 16/n
5/n = 10/16
**12/8 = 4 ½ /n

14. Answers
N = 15
N = 24
N = 8
N = 3

15. Problem Solving
Gorp is 5 parts peanuts and 2 parts raisins. How many pounds of peanuts should be mixed with one-half pound of raisins?
Peach paint is 1 part yellow to 3 parts red. How much yellow should be mixed with 4 quarts of red?

16. Continued
On a map, 1 inch equals 15 miles. How many miles apart are two towns that are 6.4 inches apart on the map?
Your car gets 32 miles to one gallon of gas. How much gas will you use on a 475 mile trip?

17. Answers p/r = p/r; 5/2 = .5/x; 5x = 1; x = .2
y/r = y/r; 1/3 = x/4; 4 = 3x; x = 1 1/3 or 1.33
i/m = i/m; 1/15 = 6.4/x; 96 = x
m/g = m/g; 32/1 = 475/x; 32x = 475; x = 14.84