Page 116 - MAT KS3 Y8 Cambridge CheckPoint

11.2 Percentage increases and decreases

8 Electricity costs are rising by 8%. Cost before rise Estimated cost
The table shows the costs for one year for four Customer ($) after rise
customers. Copy the table and fill in the last
column to show their estimated costs for one A 415
year after the price rise. Give the prices to the B 629
nearest dollar. C 390
D 812

9 A garage is reducing the prices of new cars. Calculate the new prices.

Model Old price ($) Decrease (%) New price ($)
Ace 15 800 2
Beta 17 425 3

Carro 21 280 1.5
Delta 24 172 1.8

10 A shop is selling a phone for $80. The shop increases the price by 10%.
a Find the new price.
After two weeks, the shop decreases the new price by 10%.
Read what Shen and Zalika say.

The price will go back The price now will be
down to $80. less than $80.

b Explain why Shen is wrong and Zalika is correct.
c Find the price of the phone after the decrease.

11 The same shop is selling a television for $400.
a The shop increases the price by 20%. Find the new price.
b Find 20% of the new price.
c The shop increases the price by a further 20%. Find the new price.

114 11 Percentages