Math CentralQuandaries & Queries


Question from tammy, a student:

find the quotient of 5/8 divided by7/4

Hi Tammy.

Do you know how to multiply fractions? You multiply the tops together and put that on the top of the answer and you multiply the bottoms together and put that on the bottom of the answer.

The way to divide fractions is just one extra step you have to do first: invert the second fraction.

I'll leave your question for you to do, but here is an example with different numbers:

Find the quotient of 4/5 divided by 3/10.

Step 1: invert the second fraction (turn it upside down): 10/3.

Step 2: multiply the first fraction by this inverted fraction:
4/5 x 10/3 = (4 x 10) / (5 x 3) = 40 / 15.

Step 3: simplify (reduce) it: 40 / 15 = 8 / 3 because 5 goes into both the top and bottom.

My answer is 8 / 3.

Try this method whenever you need to divide by a fraction.

Stephen La Rocque.

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