Percentage - Growth and decay

Bobo bought a gold coin for $20 000 three years ago. The value of the gold coin increased by 20% each year. The present value of the gold coin is

• $28 000

• $28 800

• $32 000

• $34 560

A watch was worth $40 000 at the beginning of 2012. Its value increased by 10% every half year. At the end of 2013, its value was

• $58 564

• $53 240

• $48 400

• $44 000

The number of new born babies in a city was 150 000 in 2012. The number of new born babies increased by 5% each year. The increase in the number of babies from 2012 to 2014 was

• 7500

• 15 375

• 157 500

• 163 375

Gloria bought a mobile phone for $3600 one years ago. The value of the phone decreased by 5% every half year. The present value of the phone is

• $3249

• $3420

• $3780

• $3969

Grace joins a fitness program. Before joining the program, her weight was 72 kg. Her weight is expected to decrease by 4% each week after joining the program. The decrease in her weight after joining the program four weeks will be ..(Correct to the nearest 0.1kg)

• 2.9kg

• 10.8kg

• 61.2kg

• 84.2kg

The profit of a company increases by 18% each year. The profit of the company is $380 000 this year. Find the profit of the company two years ago. (correct to 3 sig. fig.)

• $256 000

• $273 000

• $529 000

• $565 000

The value of a computer has decreased by 12% each year. It is known that the present value of the computer is $7000. Find the value of the computer two years ago.

• $5420

• $5580

• $8780

• $9040

The value of a vase increases by 15% each year. If the value of the vase was $34 000 in 2012, find the increase in the value of the vase from 2013 to 2015.

• $12 609.75

• $17 709.75

• $39 100

• $51 709.75

According to past record, the rainfall of an island decreased by 4% each year from 2011 to 2014. The rainfall was 3200 mm in 2014. If the percentage decrease in the rainfall remains unchanged, find the decrease in the rainfall of the island from 2011 to 2015.

• 241 mm

• 545 mm

• 3330 mm

• 3620 mm

Mr Man’s expenditure decreases by 5% each month from January to April this year. After that, his expenditure increases by 5% per month in the following three months. If his expenditure is $8000 in January, find his expenditure in July.

• $7540

• $7920

• $7940

• $8000