 Ratio, proportion and percentages

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3.5 More examples of percentages

In lots of everyday situations percentages are used to make predictions and comparisons.

Example 14

The number of casualties handled by the outpatients department of a hospital increases by approximately 8% per year. The number of casualties this year was 1920. Make a prediction for the number of casualties handled (a) next year, (b) in two years' time.

• (a) Casualties would be 100% + 8% of 1920, that is, 108% of 1920.

• This gives 1.08 × 1920 = 2073.6 = 2074 (correct to nearest whole number) as a prediction for the number of casualties next year.

• (b) Repeat this calculation again on next year's figures to find the predicted figure for the number of casualties in two years' time.

• This is 108% of 2074. 1.08 × 2074 = 2239.92 2240 casualties.

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