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.