Waiting period. Jamal is waiting to be a millionaire. He wants to know how long he must wait if

a$.$ he invests $$25,283\mathrm{.}36$ at $20\%$ today?

b$.$ he invests $$50,871\mathrm{.}92$ at $15\%$ today?

c$.$ he invests $$142,535\mathrm{.}65$ at $8\%$ today?

d$.$ he invests $$265,036\mathrm{.}47$ at $3\%$ today?

a$.$ How long will Jamal have to wait to become a millionaire if he invests $$25,283\mathrm{.}36$ at $20\%$ today?

years $($Round to the nearest whole number.$)$