# math

posted by .

How can I calculate how long an amount of money will last if I spend x dollars per month, at the same time as the pot of money is attracting interest at y percent? Is thare a formula?

Thanks

• math -

This is the same as the formula for borrowing money and repaying a monthly amount.
Let
P=principal
n=number of months it will last
y=interest rate, compounded monthly at y/12, (use 0.10 for 10% per annum)
x=monthly spending
then
p(1+y/12)^n=x((1+y/12)^n-1)/(y/12)
Unfortunately, to solve for n, you need to solve it by trial and error or Newton's method.
There exist compound interest calculators, such as:
http://www.thecalculatorsite.com/finance/calculators/compoundinterestcalculator.php#results

## Similar Questions

1. ### math

The amount of money in an account with continuously compounded interest is given by the formula A = Pert, where P is the principal, r is the annual interest rate, and t is the time in years. Calculate to the hundredth of a year how …
2. ### algebra 2

The amount of money in an account with continuously compounded interest is given by the formula A=Pe^rt , where P is the principal, r is the annual interest rate, and t is the time in years. Calculate to the nearest hundredth of a …
3. ### algebra

The amount of money in an account with continuously compounded interest is given by the formula A=Pe^rt , where P is the principal, r is the annual interest rate, and t is the time in years. Calculate to the nearest hundredth of a …
4. ### algebra

A total of \$12,000 is invested in two funds paying 9% and 11% simple interest. If the yearly interest is \$1,180, how much of the \$12,000 is invested at each rate?
5. ### math

Mr. Jones got a loan for a sum of money, and at the time of repayment he owned \$75.00 in interest. Mr. Brown borrowed three times the amount of money Mr. Jones had borrowed at the same rate of interest for twice as long a time. How …
6. ### Math

#1 Mr. Jones got a loan for a sum of money, and at the time of repayment he owed \$75 in interest. Mr. Brown borrowed three times the amount of money Mr. Jones had borrowed at the same rate of interest for twice as long a time. How …
7. ### math, algebra

If Will gives Molly \$9 dollars he will have the same amount of money as her. If Molly give Will \$9, the ratio of money she has to the money will has will be 1:2. How much money does will have in the beginning?
8. ### programming

Peter decided to save money to buy a house. Enter this amount as well as the amount he will be able to save each month. He earns 0.8% interest per month while the amount is less than R70,000 and 0,7% interest per month if the amount …
9. ### Algebra

Phyllis invested 67000 dollars, split between two different accounts. The money in the first account earns simple interest at the rate of 4 percent per year. The money in the second account earns simple interest at the rate of 6 percent …
10. ### algebra

Compound interest word problem. Suppose JJ has \$1000 that he invests in an account that pays 3.5% interest compounded quarterly. How much money does JJ have at the end of 5 years?

More Similar Questions