Section 3-4
Rates and Ratios
Math textbooks disagree slightly on the definitions of rates and ratios. Usually, a ratio is a comparison of two numbers, whereas a rate is a comparison of two quantities with different units. So, you can talk about the ratio 5:3, or the rate five miles per three hours.
Example:
A mountain climber is 3200 meters from the peak. He climbs 50 meters per hour for 8 hours per day. How many days will it be before he reaches the peak?
The first job is to figure out the rate per day.

Now divide.
UNIT RATES
A unit rate is a rate where the second quantity is one unit, such as $34 per pound, 25 miles per hour, 15 Indian Rupees per Brazilian Real, etc.
Example:
A motorcycle travels 230 miles on four gallons of gasoline. Find the average mileage per gallon.
For this problem, simply divide 230 by 4.