Using Percentages to Compare

Using Percentages to Compare

GCSE(F),

Because percentages are always out of a hundred, they can be easily used to compare different results.

Change results from two different quantities to a percentage figure, and then compare the percentages.

To obtain the percentage figure, divide the result by the total, then multiply by 100.

Examples

1. Which is greater, 35 out of 90, or 42 out of 110?

Answer: 35 out of 90

35 out of 90 = `frac(35)(90)` x 100 = 38.9% (1dp)

42 out of 100 = `frac(42)(110)` x 100 = 38.2% (1dp)

The first calculation gives the higher percentage and is therefore greater.

2. A shirt is on sale at £12 instead of the normal price of £18. A jacket is on sale for £39 instead of the normal price of £55. Which, as a percentage, offers the larger saving?

Answer: The shirt

The new price of the shirt:

12 out of 18 = `frac(12)(18)` x 100 = 66.7% (1dp)

The new price of the jacket:

39 out of 55 = `frac(39)(55)` x 100 = 70.9% (1dp)

In percentage terms, the shirt is the larger saving.