Math 015 Section 7.2 Ratios

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Math 015 Section 7.2 Ratios
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Obj To write a ratio of two quantities in
simplest form
A ratio is a comparison of two quantities that
have the same units.
A ratio can be written in three different ways

1. As a fraction
2. As two numbers separated by a colon
3. As two numbers separated by the word to

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Obj To write a ratio of two quantities in
simplest form
Write the comparison 20 pounds to 24 pounds as a
ratio in simplest form using a fraction, a colon
and the word, to.
20 pounds 24 pounds
5 6


56

5 to 6
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Obj To solve application problems involving
ratios
A company spends 20,000 a month on television
advertising and 15,000 a month on radio
advertising. What is the ratio in simplest form
of the cost of radio advertising to the total
amount spent for advertising?
Total amount spent 35,000
radio advertising total
15,000 dollars 35,000 dollars
3 7


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Obj To write rates
A rate is a comparison of two quantities that
have different units

• the units are written as part of the rate

Example Write 15 pounds of fertilizer for 12
trees as a rate in simplest form.
5 pounds 4 trees
15 pounds 12 trees

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Obj To write unit rates
A unit rate is a rate in which the number in the
denominator is 1

• to find a unit rate, divide the numerator of
  the rate by the denominator of the rate

Example Write 260 miles in 8 hours as a unit
rate
260 miles 8 hours

32.5 miles/hour
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Obj To solve application problems involving
rates
A jeweler purchased 5 ounces of gold for 1625.
Later, he sold the 5 ounces for 1720. What was
his profit per ounce?
Total profit 1720 1625

95
profit ounce
95 dollars 5 ounces

19 dollars/ounce

19/oz
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Obj To solve application problems involving
rates
At one store John can buy 3 cans of corn for
0.98. Another store has the same brand on sale
5 cans for 1.67. Which is the better price?
98 cents 3 cans
32.7 cents/can

167 cents 5 cans
33.4 cents/can

3 cans for 0.98 is the better price