SOLUTION: Clark's younger brother saved $18 per month from his paper route for the past two years. If interest is 4% compounded quarterly, how much will he have accumulated in his savings ac

It is equivalently to say that Clark deposits 18*3 = 54 dollars at the end of every quarter 
into the ordinary annuity, which provides 4% annually compounded quarterly.


So, apply the general formula for ordinary annuity future value


    FV = ,    (1)


where  FV is the future value of the annuity;  P is the quarterly payment (deposit); 
r is the quarterly effective percentage yield presented as a decimal; 
n is the number of deposits (= the number of years multiplied by 4, in this case).


Under the given conditions, P = 18*3 = 54 dollars;  r = 0.04/4 = 0.01;  n = 2*4 = 8.  
So, according to the formula (1), Clark's younger brother will get at the end of the 2-nd year


    FV =  =  447.43  dollars  (rounded to the closest cent).