Video: GCSE Mathematics Foundation Tier Pack 2 • Paper 1 • Question 30

GCSE Mathematics Foundation Tier Pack 2 • Paper 1 • Question 30

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Video Transcript

The price of a jacket is reduced by 30 percent, which is a reduction of 15 pound. Work out the normal price of the jacket.

As the reduction of 30 percent is the same as 15 pound, we can say that 30 percent of the normal price is equal to 15 pound. The normal price of the jacket will be equal to 100 percent. Therefore, we need to work out what this is equal to.

We can do this using the method of scaling. Our first step is to find a common factor of 30 and 100. In an ideal world, find the highest common factor of 30 and 100. This is equal to 10, as 10 is the highest number that divides exactly into 30 and 100.

We can work out 10 percent of the cost by dividing 15 by three, as 30 percent divided by three is equal to 10 percent. Whatever we do to one side of the equation we must do to the other. 15 divided by three is equal to five. Therefore, 10 percent of the cost is equal to five pound. 10 percent multiplied by 10 is equal to 100 percent. Therefore, we can work out the normal price of the jacket by multiplying five by 10. Five pound multiplied by 10 is equal to 50 pound. This means that the normal price of the jacket was 50 pound.

We can check this by calculating 30 percent of 50 pound. If this is equal to 15, our answer is correct. As 10 percent of 50 pound is equal to five pound, by dividing by 10, then 30 percent must be equal to 15 pound.

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