Mathematics 4024 · O Level · Exponential growth and decay

Exponential growth and decay — practice question

In 2019, Nicole earned $22000$ as her yearly income.
(a)[2]

Her accommodation spending in 2019 was $7200$. Calculate the percentage of her income that she spent on accommodation.

(b)[2]

Her yearly income of $22000$ went up by $4\%$ in 2020. Calculate her annual income in 2020.

(c(i))[2]

Nicole places $2000$ in an account. The account earns compound interest at a rate of $K\%$ per year. By the end of the first year, the balance is $2036$. Show that $K = 1.8$.

(c(ii))[3]

Calculate how many complete years must pass before Nicole has at least $2150 in the account. Show your working.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: The computation $\frac{7200}{22000} \times 100$ gives $32.7$ to $32.73$.

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