Unit 8 Lesson 3: Exercise 4

1) The population of Amber increased by 23% between 2011 and 2013. If there were 125,140 people in 2011, what was the new population in 2013?

2) A golf club is made up of 80 members and each member pays a subscription fee of £53. After a year, the members increased by 10% and the subscription fee reduced by 2%. How much did the club have at the end of the year?

3) Most speedometers in cars have an error of about 5% from the true reading. Mrs. Smith’s speedometer indicates that she is driving at 70 km/h;

a) What is the lowest speed she could be driving at?

b) What is the highest speed she could be driving at?

4) Zozoba Trades and Industry increased the salary of its workers by 12.5%. Find the new salaries of workers who previously received:

a) $25,000                                 b) $52,000

5) An increase of 20% in the price of a car raised its price to $160,200. What would have been the price if it had been reduced by 5% instead?

6) The population of a city increases by 12% each year. In 2015, the population was about 5300.

a) What was their population in 2014? b) What will be their population in 2016?

7) Prove that a 10% decrease followed by 10% increase is equivalent to a 1% decrease overall.

8) A shop advertised a garden ornament at 10% off the sale price which was $50. The shop followed up with a second advertisement with another 10% off the new price. Show that this is not the same as 20% decrease in the original price.

9) A computer system was priced at $1000 at the start of 2010. By 2011, it was 10% cheaper. If the price of the computer system reduces by 10% at the beginning of every year, what was the price of the computer system at the start of 2012?

10) A pack of biscuit which costs $1.40 normally contains 300g of biscuit. There are two special offers:

Offer A: 20% more for the same price.

Offer B: same amount for 20% off the normal price.

Which is the better offer?