8th Chapter 4 Lesson 1

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Objective
Express ratios as fractions in simplest
form and determine unit rates
Vocabulary
Ratio
A comparison of two numbers by division
Vocabulary
Rate
A comparison of two quantities with different
types of units
Vocabulary
Unit Rate
When a rate is simplified so it has a
denominator of 1
Vocabulary
Math Symbols
Approximately equal to

Example 1 Write Ratios in Simplest Form
Example 2 Write Ratios in Simplest Form
Example 3 Find a Unit Rate
Example 4 Compare Unit Rates
Express 12 blue marbles out of 18 marbles in simplest
form.
Write rate as fraction
Begin with numerator
Put fraction bar
Write denominator
Put fraction in calculator and simplify
Answer: The ratio =
1/4
Express 5 blue marbles out of 20 marbles in simplest
form.
Answer: Ratio =
1/4
Express 10 inches to 2 feet in simplest form.
Write rate as fraction
Must have same unit in
numerator as in denominator
Convert to the smaller unit
which is inches
Convert 2 feet to 24 inches.
Cancel like units
2/4
Express 10 inches to 2 feet in simplest form.
Put fraction in calculator and
simplify
Answer: The ratio =
2/4
Express 14 inches to 2 feet in simplest form.
Answer:
2/4
READING Yi-Mei reads 141 pages in 3 hours. How many
pages does she read per hour?
Write rate as fraction
Find a unit rate
141 pages ÷ 3
3 hours ÷ 3
47 pages
1 hour
Divide the numerator by the
denominator
Divide the denominator by the
denominator
Answer: Yi-Mei reads an average of 47 pages per hour
3/4
TRAVEL On a trip from Columbus, Ohio, to Myrtle
Beach, South Carolina, Lee drove 864 miles in 14 hours.
What was Lee’s average speed in miles per hour?
Answer:
61.71 miles per hour
3/4
SHOPPING Alex spends $12.50 for 2 pounds of
almonds and $23.85 for 5 pounds of jellybeans. Which
item costs less per pound? By how much?
Almonds:
Write a rate for each item
Find unit rates of each item
Jellybeans:
4/4
SHOPPING Alex spends $12.50 for 2 pounds of
almonds and $23.85 for 5 pounds of jellybeans. Which
item costs less per pound? By how much?
÷2
Almonds:
÷2
$6.25
1 pound
Divide numerator by
denominator
Divide denominator by
denominator
4/4
SHOPPING Alex spends $12.50 for 2 pounds of
almonds and $23.85 for 5 pounds of jellybeans. Which
item costs less per pound? By how much?
÷5
Jellybeans:
÷5
$4.77
1 pound
Divide numerator by
denominator
Divide denominator by
denominator
4/4
Which item costs less per pound?
By how much?
Almonds:
Jellybeans:
Jellybeans cost less
Since the denominators are
both the same (1 pound) then
compare the numerators
Since the denominators are
both the same (1 pound) then
subtract numerators
(Almonds) $6.25 – $4.77 (Jellybeans)
$1.48
Answer: Jellybeans cost $1.48 per pound less than almonds
4/4
*
SHOPPING Cameron spends $22.50 for 2 pounds of
macadamia nuts and $31.05 for 3 pounds of cashews.
Which item costs less per pound? By how much?
Answer: Cashews cost $0.90 less than macadamia nuts
4/4
Assignment
Lesson 4:1
Ratios & Rates
10 - 30 All
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