# Ellie wants to give her granddaughter a present of $$\500$$ saved in a bank account. If Ellie puts $$\350$$ in the account which earns an 8% annual interest rate, how long must she wait before the account is worth $$\500$$?

5 years 4 months

Explanation

The interest amount is $$\150$$, which is the difference between the desired amount and what Ellie originally deposits. You can use the interest formula: I = Prt, where I interest, P is principal, r is rate, and t is time (year). Just plug in I = 150, P = 350, and r = 0.08, and solve for t: 150 = 350(0.08)t =28t. Therefore t= 150/28 or approximately 5 years 4 months.