SOLUTION: A cumulative deposit account of monthly installment of rs. 3600 at 9% p.a. simple interest earns an interest of rs. 17982. Find the number of installment paid.

Question 1105355: A cumulative deposit account of monthly installment of rs. 3600 at 9% p.a. simple interest earns an interest of rs. 17982. Find the number of installment paid.
Answer by greenestamps(13195) (Show Source): You can put this solution on YOUR website!

If the monthly deposit amount is rs. 3600 and the interest is simple interest at 9% per year, then the amount of interest on each deposit each month is
rs. 3600*(.09/12) = rs. 27

If n is the number of deposits that are made, then the total amount of interest earned on the first deposit is 27(n); the total amount of interest on the second deposit is 27(n-1);...; the total amount of interest on the next-to-last deposit is 27(2), and the total amount of interest on the last deposit is 27(1).

Then the total amount of interest on all the deposits is
27(n+(n-1)+...+2+1) = 27*((n(n+1)/2)

Since the total amount of interest is rs. 17982,

Any of various methods will lead to , so the number of deposits n is 36.

RELATED QUESTIONS
)Mr x invested a total of Rs 10,000 in three different accounts , the accounts paid... (answered by Boreal)

A total of Rs 12000 is invested in two funds paying 9% and 11% simple interest. If the... (answered by mananth)

A man borrowed rs 500 from his friend and decided to return this amount in four equal... (answered by ikleyn)

I need to your help please solve these problems 1)A total of Rs 14000 invested for (answered by stanbon)

Mr. Rayan deposit an amount of Rs. 500000 in NIB. Bank offer interest rate at the rate of (answered by jorel1380)

you deposit 1800$ in a special savings account. the account earns interest at an annual... (answered by dfrazzetto)

Suppose you want to have $300,000 for retirement in 20 years. Your account earns 9%... (answered by ikleyn)

An account earns interest at a stated annual rate of 7.4%, with monthly compounding. Amy... (answered by stanbon)

Mr. Khaild will receive $8,500 a year for the next 15 years from his trust. If a 7... (answered by ikleyn)