> An interest problem?

An interest problem?

Posted at: 2014-12-05 
Assuming payments are taken at the end of the year, treat the amount as two annuities

The present value of an annuity is

PV = Pmt x (1 - 1 / (1 + i)^n) / i

http://www.tvmschools.com/formula/presen...

For the first annuity

PV =1000 x (1 - 1 / (1 + 3%)^6) / 3%

PV = 5,417.19

For the second annuity

PV =1500 x (1 - 1 / (1 + 3%)^4) / 3%

PV = 5,575.65

But this is the value at the start of year 7 so needs discounting back 6 years using the present value of a lump sum formula

PV = FV / (1 + i)^n

http://www.tvmschools.com/formula/presen...

PV = 5575.65 / (1 + 3%)^6

PV = 4,669.52

Total PV = 5,417.19 + 4,669.52 = 10,086.71

This must be the same as the balance on the account today.

(Making up this question as I go)

Bob takes out $1,000 from his bank account every year for 6 years. Suddenly he had in increase his withdrawals by $500 every year. He now takes out $1,500 every year for 4 years until his account is empty. The interest rate is 3%. What did he initially have?

I know that you are supposed to use the present worth formula, but I can't seem to organize it so that it works.

Halp.