Exploring Data: Rates & Ratios

2.8 Exploring Data: Rates & Ratios

Objectives: • Learn how to use rates to relate quantities measured in different units • Learn how to use ratios to relate quantities measured in the same units

Rate: Rates are used to compare quantities with different units by division. If a & b are 2 quantities that are different units, then the average rate of a per b is

Common Rates:

Example: If you drive 250 miles and use 10 gallons, how many miles did you get per gallon?

Reduce fraction to: 25 miles/gallon or

Example: If you earn $300 in 50 hours, how much did you earn per hour? Total pay Per hour = Total hours

Reduce when possible Divide to find pay per hour

Money Exchange Rates Example: Canada is $1.1515 to one US dollar. If you have $175 US how much Canadian?

Rate: Words cancel out and you have

If you spend all but $32.50 C$ how many US$ do you have left? Rate: US $ left Set fractions up so the unit you want left is in the numerator!

Ratio: Ratios, like rates, compare quantities by division, but ratios compare quantities measured in the same unit. In itself, a ratio has NO units. a:b a to b = = Ratios are often left as fractions with no units shown

Example: Basketball team won 10 games, lost 6 games Win to loss ratio:

Rate or Ratio? Compare the area of 2 rooms. One is 10 by 10 the other 15 by 15.

#1:

#2:

Which is easier to read? 2nd way shows that the 2nd room is over twice as large as the first (ratio)

Exploring Data: Rates & Ratios