Question

The ratio of red cars to blue cars in a parking lot was 5 : 3. If there were 40 red cars, how many blue cars were there?

Answer 1

24 blue cars

Explanation:

In this problem, one is given the ratio of red to blue cars in the parking lot. One is given the actual number of red cars, and one is asked to find the number of blue cars. One can set up a proportion; ratio to actual, then solve to find the number of actual blue cars using the method of cross-products. One can set up the proportion using the ratios, but it is easier to express the proportion as the equality of two fractions. Thus, the following equation can be formed, let the parameter (x) represent the actual amount of blue cars;

`(red)/(blue)= (5)/(3) = (40)/(x)`

Cross products,

`5x = 120`

Inverse operations,

`x = 24`