Question Video: Finding the Ratio between Two Quantities in Its Simplest Form Mathematics • 6th Grade

Given that there are 50 boys and 20 girls in a class, calculate the ratio of the number of girls to boys in its simplest form.

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Video Transcript

Given that there are 50 boys and 20 girls in a class, calculate the ratio of the number of girls to boys in its simplest form.

A ratio is a comparison of two quantities. It is usually expressed using a colon. This ratio, as it is written on the screen, would be read as the ratio of girls to boys. Let’s look at the numbers in the question. The number of girls in the class is 20. The number of boys in the class is 50. So we have the ratio 20 to 50.

The question asks us to give this ratio in its simplest form. This means that we need the two parts of the ratio to be integers with no common factors. The highest common factor of 20 and 50 is 10. So we can divide both sides of this ratio by 10. The ratio of the number of girls to the number of boys in its simplest form is two to five.

One thing you have to be careful of in this question. When we read the information, we’re told the number of boys first and then the number of girls. However, when we’re asked for the ratio, we’re asked for the girls first and the boys second.

A common error would be to give the answer five to two, which would in fact be the ratio of the number of boys to the number of girls, and therefore an incorrect answer. You must make sure that you read the information in the question carefully and write the two parts of the ratio in the correct order as they’ve been asked for.

The correct answer to this problem is two to five.

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