Colin invests £2350 into a savings account. The bank gives 4.2% compound interest for the first 4 years and 4.9% thereafter. How much will Colin have after
10 years to the nearest pound?

£3691 (nearest pound)

Step-by-step explanation:

Consider the rate of compound interest is r and the initial amount of savings is P, hence

Therefore, the final amount of savings after nth years of compund interest is

.

Given that 4.2% compound interest was used for the first 4 years to a savings of £2350, thus

Then, taking the final amount of savings previously into an initial amount for the next 6 years with 4.9% compound interest.

i'm not sure i quite understand, could you provide more information?