Ratios Lesson 7 – 1. Vocabulary Ratio: a comparison of two numbers (quantities) by division...
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Transcript of Ratios Lesson 7 – 1. Vocabulary Ratio: a comparison of two numbers (quantities) by division...
Ratios
Lesson 7 – 1
Vocabulary
• Ratio: a comparison of two numbers
(quantities) by division
• Equivalent Ratios: ratios showing the
same relationship between two quantities.
(have the same value)
How to write a ratio?
3 ways!Example: ratio of 5 girls to 3 boys
5 to 3 5:3
Also possible with algebra, a to b
a to b a:b
3 5
b a
Need to Know about Ratios!
# 1: order matters. Follow the order from the question.
# 2: label your work. This will help when you set up proportions.
# 3: write the ratio in simplest form!
# 4: DON’T change to mixed numbers. It is ok to have improper fractions when writing a ratio.
Practice writing ratios
In the SMS choir, there are 24 sopranos, 2 tenors, 4 basses, and 15 altos. Find each ratio.
# 1: What is the ratio of tenors to sopranos?
# 2: What is the ratio of altos to members in the choir?
# 3: What is the ratio of sopranos to altos?
12 1
3 1
5 8
Rates
Lesson 7 – 2
Vocabulary
• Rate: a ratio that compares two
quantities measured in different units
• Unit Rate: a rate simplified to a
denominator of 1 unit.
• Example: I can type 200 words in 4 minutes
My Rate = Unit Rate = 4 minutes200 words
1 minute50 words
‘per’ means to ‘divide by’
Example: miles per hour means to divide number of miles by number of hours. So, if you drive 360 miles in 8 hours, and you want miles per hour, then:
Answer: 45 miles per hour or 45 mph
360 miles8 hours
Find the Better Buy!
Find the unit rate to determine the better buy.
# 1: 5 pairs of socks for $4.95
8 pairs of socks for $7.95
# 2: 4 CDs for $60
6 CDs for $75
5 CDs for $70
3 CDs for $40
5 pairs for $.99 per pair
6 CDs for $12.50/ CD
$13.33/CD
$14.00/CD
$12.50/CD$15.00/CD
$0.994/pair
$0.99/pair