Practice questions 28.2


1. Find the percentage increase or decrease that occurs in each of the following cases. Give your answer to two decimal places where necessary.


(i) 80 kg increases to 100 kg (ii) 9 000 km decreases to 7 200 km (iii) €85 reduces to €82 (iv) 100 cm3


increases to 350 cm3


(v) 10 m reduces to 9⋅5 m (vi) €72 000 reduces to €48 000


2. Shaun has a fl ock of 64 sheep. He has lost eight of them. What percentage of the fl ock has he lost? Give your answer to one decimal place.


3. Last month Emma earned €150, but this month she earned €180. What percentage increase in pay did she receive?


4. Ciaran buys shares in a company for €82 000. He sells them for €104 000. What was the percentage increase of the shares? Give your answer to two decimal places.


5. Elvis bought a car for €3 400. He sold it two years later for €2 000. What was the percentage decrease of the car? Give your answer to one decimal place.


6. Mia bought a mobile home for €54 500. Eight years later, she sold it for €37 200. By what percentage had the price of the mobile home depreciated (decreased)? Give your answer to one decimal place.


7. Robin wants to trade in some old console games to buy a new headset. The shop off ers to buy his games for 45% of their original value. Robin trades in four games. The original price he paid for each game is as follows.


Game


Pacey Man Speed Racer Wonder Falls


Super Maria Cars Total (€)


Original price €29⋅99


€34.99 €19⋅99 €24⋅99 ?


(i) The shop off er Robin €43·98 for all four games. Verify that this off er is not equal to 45% of their original value.


(ii) Based on the value off ered of €43⋅98, what percentage of the original price is the shop purchasing the games for? Give your answer to the nearest whole number.


(iii) If you were Robin, how would you explain how to calculate the correct purchase price of the games to the shop assistant?


8. One hundred years ago, the average height of a female in Ireland was 154 cm, and the average height of a male was 166·4 cm. Today, the average height of a female is 165·1 cm and the average height of a male is 178·9 cm.


Calculate the percentage increase in the height of (i) a female and (ii) a male over the past 100 years. Give your answers to two decimal places.


9. In 1970, the area of the Amazon rainforest was approximately 4·1 million km2 its area had decreased to 3·3 million km2


. In 2019, .


Calculate the percentage decrease in the area of the Amazon rainforest. Give your answer to one decimal place.


450


Linking Thinking 1


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