SOLUTION: mike wants to sabe 20.000 for a motorcycle. determine his monthly payment required if the bank offers a three year investment at 4,9% per year, compounded monthly.

I will assume that Mike deposits a certain amount at the end of each month during three years.


It is a classic Ordinary Annuity saving plan. The general formula is 


    FV = ,    


where  FV is the future value of the account;  P is the monthly payment (deposit); r is the monthly percentage yield presented as a decimal; 
n is the number of deposits (= the number of years multiplied by 12, in this case).


From this formula, you get for the monthly payment 


    P = .     (1)


Under the given conditions, FV = $280,000;  r = 0.049/12;  n = 3*12.  So, according to the formula (1), you get for the monthly payment 


    P =  = $516.86  (rounded to the nearest greatest cent).


Answer.  The necessary monthly deposit value is $516.86.


Note that of projected $20,000, the total of Mike's deposits will be only  3*12 times $516.86, i.e. about 3*12*516.86 = 18606.96 dollars.
The rest is what the account will earn/accumulate in 3 years.