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

User DukeLover
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2 Answers

7 votes

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.

User Soony
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7.6k points
4 votes

Answer:

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.

User Marty Trenouth
by
7.4k points

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