Every month, a particular interest bearing account earns 0.5 percent interest on the average balance for that month. The function B(t)=7.5t^2 -300t +5000 represents one investor's balance in this account during the month of July. B(t) gives the number of dollars in the account on day, t, with t=0 being the beginning of the first day. How much interest will the account earn this month?

Question

Every month, a particular interest bearing account earns 0.5 percent interest on the average balance for that month. The function B(t)=7.5t^2 -300t +5000 represents one investor's balance in this account during the month of July. B(t) gives the number of dollars in the account on day, t, with t=0 being the beginning of the first day. How much interest will the account earn this  month?