$800 is deposited in an account
that pays 9% annual interest,
compounded annually. Find the
balance after four years.

The balance after four years is $1129.27

Step-by-step explanation:

The formula for compound interest, including principal sum, is

∵ $800 is deposited in an account

∴ P = 800

∵ The account pays 9% annual interest

∴ r = 9% = 9 ÷ 100 = 0.09

∵ The interest is compounded annually

∴ n = 1

∵ The time is 4 years

∴ t = 4

- Substitute the values of P, r, n, and t in the formula above

∵

∴

∴ A = 1129.265

∴ The balance after four years is $1129.27

answer: 177/8

step-by-step explanation: