if $2000 left in account for 4 years earned interest of $400, then how much interest would be earned in 5 years?

Answer 1

If it's simple interest, not compounded, then I = prt, principal X rate X time, and so it's proportional to the time.

$400 / 4 yrs = X / 5 yrs, and X = $500.

On the other hand, if compounded interest, would need more information such as the period of compounding.