Transcript PowerPoint

Objective- To compare ratios and rates.
Ratio - A comparison of two whole numbers
in the same units.
5 girls to 7 boys
4 Possible Ways to Write a Ratio
5
5: 7
5 to 7
7
sometimes . . .
5 out of 12
as in 5 girls out of 12 students
Simplify each ratio below.
10
50

1)
3
15
24
4
2)

18
3
3) 12 out of 40
3
12

10
40
4) 18 to 3
18
6

3
1
4 weeks 28 days

5)
4 days
4 days
7
28

1
4
6) 16 inches  16 inches
2 feet
24 inches
16
2

24
3
Ratio
Rate
20 in. 20 in.
5


3 ft.
36 in.
9
300 mi.
 60 mi./ hr.
5 hr.
- a comparison of two
whole numbers in the
same units.
- always written as two
numbers.
- a comparison of a number
to one in different units.
3
2
4:9
15 to 1
- always written as a single
number on a per unit basis.
30.7 words / min.
1
3 children / family
2
- never write the units.
- always write the units.
- reduce to simplify.
- divide to simplify.
Find the unit rate.
1) 84 students in 4 classrooms
84 students
 21 students / classroom
4 classrooms
2) $30 for 8 lunches
$30
 $3.75/ lunch
8 lunches
3) 15,000 cars sold by 2000 dealers
15,000 cars
 7.5 cars / dealer
2000 dealers
Reciprocal Rates
8 oranges for 2 dollars
Unit Rate
Reciprocal Rate
$2
8 oranges
 $0.25 / orange
$87.50 for 5 tickets
Unit Rate
$87.50
5 tickets
 $17.50/ ticket
8 oranges
$2
 4 oranges / dollar
Reciprocal Rate
5 tickets
$87.50
 0.057 tickets / dollar
Rate Multiplication
Your heart beats 70 beats/min. How many
beats per hour is this?
Start
70 beats
1 min.
Finish

60 min.
1 hr.
Rates
60 min.
1 hr.

4200 beats
1
hr.
4200 beats / hr.
Rate Multiplication
Joe reads 12 pages per day. How long
would it take him to read a 684 page book?
Start
684 pages
1
Finish

1 day
12 pages
Rates
12pages
1 day

684
days
12
57 days
Rate Multiplication
The world record for the 100 yard dash
is 9.4 seconds. How fast is this in miles/hr?
Start
Finish
1 mi.
100 yds. 3 ft.
60 sec . 60 min .
mi.





9.4 sec . 1 yd. 5280 ft. 1 min .
1 hr.
hr.
100(3)(1)(60)(60)

 21.76 miles / hour
9.4(1)(5280)(1)(1)
Rates
3 ft.
1 yd.
5280 ft.
1 mi.
60 sec.
1 min .
60 min.
1 hr.