Alazar deposited 2000 birr in a bank. After 6 months, he collected 2120 birr. We need to find the rate of simple interest the bank paid per annum.

1. Problem Description

Alazar deposited 2000 birr in a bank. After 6 months, he collected 2120 birr. We need to find the rate of simple interest the bank paid per annum.

2. Solution Steps

Let P be the principal amount, which is 2000 birr.

Let A be the amount after 6 months, which is 2120 birr.

Let I be the simple interest earned in 6 months.

$I = A - P = 2120 - 2000 = 120$ birr.

Let r be the annual interest rate.

Let t be the time period in years, which is 6 months or 0.5 years.

The formula for simple interest is:

$I = P \times r \times t$

We have $120 = 2000 \times r \times 0.5$

$120 = 1000 \times r$

$r = \frac{120}{1000} = 0.12$

To express r as a percentage, we multiply by

1

0

0. $r = 0.12 \times 100 = 12\%$

3. Final Answer

12%