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