$($a$)$ You deposit $$5000$ in a savings account that earns $13\%$ simple interest per year. What is the minimum number of years you must wait to double your balance

$($b$)$ You deposit $$5000$ in a savings account that earns $13\%$ compound interest per year. What is the minimum number of years you must wait to double your balance?

$($Please keep two decimal places$)$