Kofo saved 30 naira with the post office savings bank for 2 years. At the end of this period, he received 2 naira 40kobo as simple interest on his money. At what rate percent per annum was the interest paid?
The formula to calculate simple interest is:
Simple Interest = Principal × Rate × Time
Let's call the rate percent per annum "r", and the time period in years "t".
Given that Kofo saved 30 naira and received 2.40 naira as simple interest after 2 years, we can set up the equation:
2.40 = 30 × r × 2
To find the rate percent per annum "r," we divide both sides of the equation by (30 × 2):
2.40 / (30 × 2) = r
0.04 = r
So, the rate percent per annum is 4%.