1. Ratios and Rates
4 : 7
100 km/h __ 3 4
11 : 14

2. By definition:
A ratio is a fraction that compares two numbers with the same units.
A rate compares two numbers with different units

3. In this classroom, write the ratio for:
Boys to girls
Dark hair to light hair
Short hair to long hair

4. From a pocket full of change, write the ratios for -
Dimes to quarters –
Nickels to dimes –
Loonies to pennies –

5. Rates compare numbers of different units:
100 km / h (401)
$50.00 / week (allowance)
$8.00 / person (movies)

6. Ratios can be used to analyze information
Consider 2 baseball players:
Player 1
77 hits in 149 bats
Player 2
189 hits in 417 bats
Who is the better hitter?

7. Player 2
189 hits in bats 417 bats
Player 1
77 hits in 149 bats
Who is the better hitter? 77
149
189
417
= 0.517
= 0.453

8. When rates are expressed as unit rates, comparisons can be made.
For Example:
$67.50 for 6 hours work or
$85.00 for 7 hours work
Which is the better job?

9. Which is the better deal?
200g of popcorn for $1.00 or
750g of popcorn for $2.70

10. RRs are in lowest terms when the GCF is 1
4 : 8 =
1 : 2
10 : 25 =
2 : 5
6 : 48 =
1 : 8
7 : 21 =
1 : 3
Equivalent ratios form a proportion
Proportions can be solved for unknown amounts

11. Page 67
[1-27] odd
28,29
31,37,39
42,46
Hand in…

12. Proportions

13. Find the unknown quantity:
Orange juice powder and water must be mixed in the ratio 1:4
If you have 3 cups of mix, how much water do you need?
Mix =
Water 1 = 4 3 X
1X = 12
X = 12

14. How much mix will you need to go with 10 cups of water=
Water 1 = 4 X 10
4X = 10 1
4X = 10 1
X = 10 4
X = 2.5

15. Proportions can be reduced to a unit rate.
Proportions can then be compared

16. Sheets

17. Rates For this assignment: Copy down all the text in black
Answer the homework questions assigned on the last slide
Show Mr. Stokes both when you are finished

18. A ratio compares 2 numbers in the same unit (3:4 or 2:13)
A rate compares two numbers in different units

19. Speed limit on the 401 Pay at McDonald’s 100 km / hour
km are one unit and hours are the other
Pay at McDonald’s
$7.00 / hour
Dollars are one unit and hours are the other

20. Rates are most useful when they are written as a unit rate
Rates are most useful when they are written as a unit rate. To determine the unit rate, use division

21. Suppose you make $45.00 in 5 hours.
How much do you make per hour?
To find pay per hour:
Pay
hour = 45 5 =
$9 / hour

22. Suppose 12 CDs cost $14.99
How much does 1 CD cost?
cost CD
14.99 12 =
= $1.25 / CD

23. Rates can be expressed in unit rates (used for comparisons)
180 km in 2 hours
180 / 2 = 90 km / h
$3.60 for 6 muffins
3.60 / 6 = $.60 / muffin

24. Homework
Page

25. Rates
Spending money…

26. By definition:
A ratio is a fraction that compares 2 numbers with the same units.
A rate compares 2 numbers with different units

27. For comparisons, it is usually better to express the numbers in a unit rate
To determine the unit rate, divide the 2 quantities being examined

28. For example: A: 10 pack of CDs costs $11.99.
B: 12 pack of CDs costs $12.99.
Which is the better deal? (price/CD)

29. A:
11.99
Price
$1.20/CD = = 10 CD B:
12.99
Price
$1.08/CD = = 12 CD
B is a better deal!

30. Ex 2: Laundry soap comes in 3 sizes and prices. Determine the best buy:
Size (loads)
Cost ($) A:
5.49 B:
8.49 C:
9.99

31. The best buy will have the lowest cost per load.

32. A:
5.49
Price
$0.55/load = = 10
load B:
8.49
Price
$0.42/load = = 20
load C:
9.99
Price
$0.27/load = = 37
load

33. C is the best deal

34. Page 11
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