# Arithmetic series question

• Apr 24th 2009, 08:55 AM
Arithmetic series question
A common interest in constant. It's \$25 per year. Initial deposit is \$500. After 10 years the amount of money in the account was \$750. Using the arithmetic sequence which is tn= a+(n-1)d. Can you find how much money is in the account after 20 years?
• Apr 26th 2009, 10:24 PM
SengNee
Quote:

A common interest in constant. It's \$25 per year. Initial deposit is \$500. After 10 years the amount of money in the account was \$750. Using the arithmetic sequence which is tn= a+(n-1)d. Can you find how much money is in the account after 20 years?

It's \$25 per year.
$d=+25$

Initial deposit is \$500.
$a$ is greater than or equal to 500.

After 10 years the amount of money in the account was \$750.
$T_n=a+(n-1)d$
$T_{10}=a+(10-1)d$
$a=$?

After 20 years.
$T_{20}=$?