Respuesta :
Answer:
£3691 (nearest pound)
Step-by-step explanation:
Consider the rate of compound interest is r and the initial amount of savings is P, hence
[tex]P \ + \ P \ \times \ r \ = \ P \ (\ 1 \ + \ r \ ) \qquad (Final \ amount \ for \ the \ 1st \ year ) \\ \\ \ P \ (\ 1 \ + \ r \ ) \ + \ P \ (\ 1 \ + \ r \ ) \ \times \ r \ = \\ \ P\ ( \ 1\ + \ r \ ) \ ( \ 1 \ + \ r \ ) \ = \ P \ {( \ 1 \ + \ r \ )}^2 \qquad (Final \ amount \ for \ the \ 2nd \ year) \\ \\ \ P \ {(\ 1 \ + \ r \ )}^2 \ + \ P \ {(\ 1 \ + \ r \ )}^2 \ \times \ r \ = \\ \ P\ {( \ 1\ + \ r \ )}^2 \ ( \ 1 \ + \ r \ ) \ = \ P \ {( \ 1 \ + \ r \ )}^3 \\ \\ (Final \ amount \ for \ the \ 3rd \ year)...[/tex]
Therefore, the final amount of savings after nth years of compund interest is
[tex]P \ {( \ 1 \ + \ r \ )}^n[/tex].
Given that 4.2% compound interest was used for the first 4 years to a savings of £2350, thus
[tex]Final \ amount \ for \ the \ first \ 4 \ years \ = \ 2350 \ {( \ 1 \ + \ \frac{4.2}{100} \ )}^4 \ = \ 2770.36[/tex]
Then, taking the final amount of savings previously into an initial amount for the next 6 years with 4.9% compound interest.
[tex]2770.36 \ {( \ 1 + \frac{4.9}{100} \ )}^6 \ = \ 3691.40 \ = \ 3691 \ (nearest \ pound)[/tex]
