Question 810631
For the last five years Larissa has been depositing $135 at the end of every month into a savings account that earns 5.5% compounded quarterly.
If she continues this savings plan for another eight years, how much will she have in her savings account altogether? 
:
So I understand they want how much she has in 13 yrs. 
The payments are made monthly, but the interest compounds quarterly which complicates things. 
:
We can get around this by saying that amt is 3*135=$405 deposited each quarter
and there are 13 * 4 = 52 quarters.

The formula
A = P*{{{((1+i)^t-1)/i}}}, where
i = interest rate per period in decimal form
t = total time periods of the annuity

Interest rate for each period will be .055/4 = .01375
T = 13 * 4 = 52 quarters
:
A = 405*{{{(1.01375^52-1)/.01375}}}
A = 405 * 75.21844
A = $30,463.47
:
This does not quite agree with the annuity feature in my Ti-83 where
you can have 12 monthly payments and quarterly paid interest
It got: $30,602.67