GCSE · Percentages & growth

Compound growth and decayExam-style questions

Why repeated percentage change is a power of the multiplier, how compound interest differs from simple interest, and how to build growth and decay models.

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19 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try

DifficultyAll Level 1 Level 2 Level 3 Level 4 Level 5

1
Ola has £ $2000$ to invest for $4$ years.

Account A pays $3\%$ compound interest per year. Account B pays $3.2\%$ simple interest per year.

Which account gives more interest over the $4$ years, and by how much? (4 marks)
Level 4 · 4 marksTry it
2
Marcus borrowed some money.

At the end of each year, interest of $4\%$ of the amount Marcus owed was added to the loan.

Marcus paid back £1500 at the end of the first year, after the interest for that year had been added.

He paid back £2000 at the end of the second year, after the interest for that year had been added.

Marcus then owed £4552

Work out how much money Marcus borrowed.

You must show all your working.

(4 marks)
Level 4 · 4 marksTry it
3
A car is worth £18 500. It depreciates by 14% of its value each year. Work out the value of the car after 4 years. Give your answer to the nearest pound.
Level 4 · 3 marksTry it
4
£6000 is invested for 5 years.
- Account A pays 4% simple interest per year.
- Account B pays 3.6% compound interest per year.
Work out which account earns more interest over the 5 years, and by how much. Give your answer to the nearest penny.

You must show your working.
Level 4 · 4 marksTry it
5
A colony of bacteria has a population of 8000 and grows by 5% each hour.

(a) Write down an expression for the population after $t$ hours.

(b) Work out the population after 6 hours. Give your answer to the nearest whole number.
Level 4 · 3 marksTry it

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