# Thread: series problem. thanks for any help

1. ## series problem. thanks for any help

Mike and Amanda want to purchase a house. Suppose they invest 400 dollars per month into a mutual fund. How much will they have for a downpayment after 3 years if the per annum rate of return of the mutual fund is assumed to be 10 percent compounded monthly?

2. ## I am not good at money problems

Originally Posted by waite3
Mike and Amanda want to purchase a house. Suppose they invest 400 dollars per month into a mutual fund. How much will they have for a downpayment after 3 years if the per annum rate of return of the mutual fund is assumed to be 10 percent compounded monthly?
but could it be $\sum_{n=0}^{36}{400\bigg(\frac{11}{10}\bigg)^{n}}= 132000$

3. what do you get for the final value i keep summing it up and i cant get the right answer. thanks

4. ## Just so you know

Originally Posted by waite3
what do you get for the final value i keep summing it up and i cant get the right answer. thanks
It would be $\sum_{n=0}^{36}{400\bigg(\frac{11}{10}\bigg)^{n}}= 400\cdot\frac{\frac{11}{10}\bigg(1-\bigg(\frac{11}{10}\bigg)^{36}\bigg)}{1-\frac{11}{10}}$