A ratio is a way to compare two numbers, measurements or quantities. When we write a ratio, we divide one number by another and express the answer as a fraction. There are two distinct ratios in the example below.
Using Ratios as an Explanation
Nadia is counting out money with her little brother. She gives her brother all the nickels and pennies. She keeps the quarters and dimes for herself. Nadia has four quarters and six dimes. Her brother has fifteen nickels and five pennies and is happy because he has more coins than his big sister. How would you explain to him that he is actually getting a bad deal?
Notice that even though the denominator is one, we still write it out and leave the ratio as a fraction instead of a whole number. A ratio with a denominator of one is called a unit rate .
The price of a Harry Potter Book on Amazon.com is $10.00. The same book is also available used for $6.50. Find two ways to compare these prices.
Comparing Length and Width
A tournament size shuffleboard table measures 30 inches wide by 14 feet long. Compare the length of the table to its width and express the answer as a ratio.
A family car is being tested for fuel efficiency. It drives non-stop for 100 miles and uses 3.2 gallons of gasoline. Write the ratio of distance traveled to fuel used as a unit rate .
Write the following comparisons as ratios. Simplify fractions where possible.
- $150 to $3.
- 150 boys to 175 girls.
- 200 minutes to 1 hour.
- 10 days to 2 weeks.
Write the following ratios as a unit rate.
- 54 hotdogs to 12 minutes.
- 5000 lbs to 250 square inches.
- 20 computers to 80 students.
- 180 students to 6 teachers .
- 12 meters to 4 floors .
- 18 minutes to 15 appointments.
To view the Review answers, open this PDF file and look for section 3.10.