Marilee takes all the money from her piggy bank and puts it into a savings account at her local bank. The bank promises an annual interest rate of 2.5% on the balance, compounded semiannually. How much will she have after one year if her initial deposit was $400?
A) $390.06
B) $420.25
C) $410.06
D) $420.50
Can you leave an explanation too?