Question

The ratio of boys to girls is 4:5 if there are 20 boys in the class find the number of girls. Show workings

Answer 1

Answer: 25 girls are in the class

Step-by-step explanation: You can set up the ratio 4:5 as a fraction,
`(4)/(5)` to find your answer. You are given the fact that 20 boys are in the class so now you can solve 2 ways.

Option 1 - Set up the equation algebraically as
`(20)/(x)`, where x = number of girls and set that equal to
`(4)/(5)`. This way allows you to see that the fraction must have the same ratio as 4:5. You can see that 4 x 5 = 20, so the multiple factor is 5. The variable x must equal 5 x 5, so x = 25.

Option 2 - Multiply the amount of boys given to you by the reciprocal of the ratio. Instead of using
`(4)/(5)`, you have to use
`(5)/(4)` because there are more girls than boys in the class. This allows you to finish the problem by multiplying 20 x
`(5)/(4)` to get the result of
`(100)/(4)`, which you may know simplifies into 25.

Answer 2

25 girls

Explanation:

We Know

The ratio of boys to girls is 4:5. For every 4 boys, there are 5 girls.

To get from 4 to 20, we multiply by 5.

We Take

5 x 5 = 25 girls

So, there are 25 girls in class.