At a simple interest rate of 10% per year, how many years will it take for a principal amount of Tk. 500 to earn an interest amount of Tk. 100?

A 3

B 2

C 2(1/2)

D Cannot be determined

Correct Answer: Option B

here. at 10% rate, interest of 500 tk in 1 yr = 10 X 500/100 = 50 tk
so, 50 tk interest in 1year
100 tk interest in 100/50 = 2 yr