Proportions and Ratios in Word Problems

Front

What is a ratio?

Back

A ratio is a comparison of two quantities by division, showing how many times one value contains or is contained within the other.

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal.

Front

How do you solve a proportion?

Back

To solve a proportion, cross-multiply the terms and set the products equal to each other.

Front

If 13 out of 20 homes have a personal computer, how do you find the expected number of homes with a computer on a street with 60 homes?

Back

Set up a proportion: 13/20 = x/60, then cross-multiply and solve for x.

Front

What is the formula to find the total amount earned based on a rate and time?

Back

Total Earnings = (Earnings per time period) x (Number of time periods).

Front

If you earn $15 every 3 weeks, how much do you earn in 5 weeks?

Back

First, find the earnings per week: $15/3 weeks = $5/week. Then, multiply by 5 weeks: $5 x 5 = $25.

Front

What does it mean if the ratio of red fish to blue fish is 3:5?

Back

It means for every 3 red fish, there are 5 blue fish.

Front

If there are 20 blue fish and the ratio of red to blue fish is 3:5, how many red fish are there?

Back

Set up the ratio: 3/5 = x/20. Cross-multiply to find x: 3*20 = 5x, so x = 12.

Front

What is the first step in solving a word problem involving ratios?

Back

Identify the quantities involved and the relationship between them.

Front

How can you check if your answer to a proportion is correct?

Back

Substitute your answer back into the original proportion to see if both sides are equal.