Some principal becomes Tk. 1,750 as profit-principal in 5 years and Tk. 2,250 as profit-principal in 10 years. Find the rate of profit.

Question: Some principal becomes Tk. 1,750 as profit-principal in 5 years and Tk. 2,250 as profit-principal in 10 years. Find the rate of profit.

Solution:
Given,
Principal + Profit for 5 years = 1,750
Principal + Profit for 10 years = 2,250

So the profit of 5 years, I = 2250 - 1750 = Tk. 500
So the principal, P= 1750 - 500 = Tk. 1250

∴ The rate of profit, r = (I × 100)/(P × n)
= (500 × 100)/(1250 × 5)
= 50000/6250
= 8%