Transcript Ratio 5.2 Rate

Ratios and Rates
Section 5.1 & 5.2
Objectives:
• Solve problems involving average
speed, distance, and time. (AF 4.2)
• Choose an appropriate unit measure
and use ratios to convert within and
between measurement systems.
(MG 1.0)
• Compare measures within and
between measurement items
(MG 1.1)
Words to
know ~
• Ratio – a comparison of a number “a” and a
nonzero number “b” using division.
Example – 12 games to 7 games ;
12 to 7; 12:7
• Rate – a type of ratio that compares two
• quantities that have different kinds of
units of measure.
Example – 100 miles in 2 hours
• - 6 pencils for $1.40
• Voting – Barack Obama won 333 electoral
Writing a Ratio
votes while John McCain won 156. What’s
the ratio of Obama’s votes to McCain’s
votes?
• Ratio – Obama votes =
McCain votes
Ratio can be written also as 111:52 , or
“111 to 52”
Rewriting with
the same units
• A map shows the distance between the
classroom and the bathroom as 16 inches.
In reality, the distance is 4 yards.
MUST CONVERT TO
THE SAME UNIT OF
MEASURE!!!
Finding a Rate
• You and your family drove 400 miles in 8
hours.
• What was the average rate of speed?
Reduce the numbers.
Summary:
Ratio is ….
Rate is ….
Finding a Unit
Rate
• A 6 pack of soda costs $1.60. A 12 pack
of soda costs $ 3.00. Which is the better
buy?
Finding a Unit
Rate
Golf balls can be purchased in a 3-pack
for $4.95 or a 12-pack for $18.95. Which
pack has the lower unit price?
price for package
number of balls
=
$4.95
3
price for package
number of balls
=
$18.95
12


$1.65
$1.58
The 12-pack for $18.95 has the lower unit price.
Finding a Unit
Rate
John can buy a 24 oz bottle of ketchup
for $2.19 or a 36 oz bottle for $3.79.
Which bottle has the lower unit price?
price for bottle
number of ounces
=
price for bottle
number of ounces
=
$2.19
24
$3.79
36

$0.09

$0.11
The 24 oz jar for $2.19 has the lower
unit price.
Practice
Identify if the problems are rates or ratios.
Practice
• Write each fraction in simplest terms.
Summary
• Remember that a ratio is a comparison of two numbers.
Example = number of A’s compared to the number of B’s
• Remember that a rate is a type of ratio that
compares two quantities that have different kinds of units
of measure.
• Example = 2 pairs of pants for $25. (comparing the number of
pants to the dollar amount.)
Lesson Quiz
Write each ratio in simplest form.
1
1. 22 tigers to 44 lions
2
30
2. 5 feet to 14 inches
7
3. Meka can make 6 bracelets per half hour. How many bracelets can
she make per hour?
12
Estimate each unit rate.
4. $2.22 for 6 stamps
$0.37 per stamp
5. 8 heartbeats in 6 seconds
 1.3 beats/s
Find each unit price. Then tell which has the lower unit price.
6. A half dozen carnations for $4.75 or a dozen for $9.24
7. 4 pens for $5.16 or a ten-pack for $12.90.
a dozen
They cost the same.
Activity
• Using the grocery store flyers (with a partner), create 3
rates and 3 ratios.
• Exchange them with another team.
• Solve the other team’s rates and ratios.