Question

Cynthia invests some money in a bank which pays 5% compound interest per year. She wants it to be worth over £8000 at the end of 3 years. What is the smallest amount , to the nearest pound , she can invest?

Answer 1

`\bf 8000=P\left(1+(0.05)/(1)\right)^(1\cdot 3)\implies 8000=P(1.05)^3\implies \cfrac{8000}{1.05^3}=P\\\\\\6910.70\approx P\implies  \stackrel{\textit{rounded up}}{6911 = P}\qquad  therefore\qquad 6911~~\leqslant ~~P`