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Ratio, proportion and percentages
Ratio, proportion and percentages

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3.4.1 Try some yourself

Activity 24

A new train operator boasts ‘Train times reduced by 12%’. Decrease 90 minutes by 12%. Give your answer as minutes and seconds.

Answer

A 12% decrease would reduce it to 88% of the original time, i.e. 0.88 × 90 = 79.2 minutes.

0.2 of a minute = 0.2 × 60 = 12 secs.

So 79.2 minutes = 79 minutes and 12 secs.

Activity 25

The population of a small town is 4650. It is predicted that the population will decrease by approximately 4% each year. What is the population likely to be after (a) one year, (b) two years?

Answer

  • (a) Population after 1 year is likely to be

  •   (100% − 4%) of 4650,

  • i.e. 96% of 4650,

  • which is 0.96 × 4650 = 4464 people.

  • (b) Population after 2 years is likely to be

  •   96% of 4464,

  • i.e. 0.96 × 4464 = 4285.44 people,

  • but you can’t have 0.44 of a person. So approximately 4285 people.