1. Math 015 Section 7.2 Ratios

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

3. 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 pounds = =
5:6 =
5 to 6

4. 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 = =

5. A rate is a comparison of two quantities that have different units
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.
15 pounds trees
5 pounds 4 trees =

6. 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

7. Obj: To solve application problems involving rates
A jeweler purchased 5 ounces of gold for $ Later, he sold the 5 ounces for $ What was his profit per ounce?
Total profit = 1720 – 1625 =
$95
profit ounce
95 dollars 5 ounces = =
19 dollars/ounce
= $19/oz

8. Obj: To solve application problems involving rates
At one store John can buy 3 cans of corn for $ Another store has the same brand on sale 5 cans for $ 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