Question $1$a$)($Compound interest$)$

To what amount will the following investments accumulate? $($a$)$ $$775$ invested for twelve years at $12\%$ compounded annually $($b$)$ $$21,000$ invested for five years at $5\%$ compounded annually

Question $1$b$)($Compound value solving for n$)$

How many years will the following take? $($a$)$ $$100$ to grow to $$298\mathrm{.}60$ if invested at $20\%$ compounded annually $($b$)$ $$53$ to grow to $$78\mathrm{.}76$ if invested at $2\%$ compounded annually

$1$c$)$

At what annual rate would the following have to be invested? $($a$)$ $$50$ to grow to $$280\mathrm{.}20$ in twenty years $($b$)$ $$200$ to grow to $$497\mathrm{.}60$ in five years