Video: AQA GCSE Mathematics Foundation Tier Pack 1 • Paper 1 • Question 10

Write 48 cm as a fraction of 4 m. Give your answer in its simplest form.


Video Transcript

Write 48 centimetres as a fraction of four metres. Give your answer in its simplest form.

Before we start this question, we need to remember the conversion that 100 centimetres is equal to one metre. Multiplying both sides of this conversion by four tells us that four metres is equal to 400 centimetres. We now have both of our values written in the same units.

We were asked to write 48 centimetres as a fraction of four metres. This means that we need to write 48 over 400. We’ve now completed the first part of the question. However, we were also asked to give the answer in its simplest form. This involves cancelling or breaking down the fraction.

To ensure that we have an equivalent fraction, we need to remember that whatever we do the top we must do to the bottom. When we are dividing the numerator, we must divide the denominator by the same number. There are lots of ways of cancelling this fraction. You might have noticed that both 48 and 400 are divisible by four. 48 divided by four is equal to 12, as 12 multiplied by four equals 48. Dividing 400 by four gives us 100.

This fraction can be simplified or cancelled again. Both two and four divide into the numerator and denominator. This means that we could divide the top and bottom either by two or by four. Dividing 12 by four gives us three, and dividing 100 by four gives us 25. Remember, dividing by four is the same as finding a quarter of a number. And we know that one-quarter of 100 is 25. The numbers three and 25 have no common factor apart from one. Therefore, the fraction is now in its simplest form. 48 centimetres as a fraction of four metres in its simplest form is three twenty-fifths or three over 25.

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