Question 366573
YOU INVEST 4000 DOLLARS AT 6% COMPOUNDED MONTHLY, WHEN WILL YOU HAVE 25000 DOLLARS?

Let x = no. of months 

A = pr^t

           25,000 = 4000(1+.06/12)^x
           6.25   = (1.005)^x
        (1.005)^x = 6.25
    Log[(1.005)^x = 6.25]
      x Log 1.005 = Log 6.25

               x  = 367.44 say 368

You will have $25,000 after 368 months ( 30 years & 8 months)