Answer:
16,000.
Explanation:
Let's denote the principal sum of money as P.
The compound interest on the sum compounded semi-annually in one year at 10% per annum can be calculated using the formula:
A₁ = P(1 + r/n)^(nt)
Where:
A₁ is the amount after one year, r is the annual interest rate (10% or 0.10), n is the number of times interest is compounded per year (2 for semi-annual compounding), and t is the number of years (1 in this case).
Similarly, the compound interest on the sum compounded annually in one year at the same rate can be calculated using the formula:
A₂ = P(1 + r)^t
Given that the compound interest compounded semi-annually is Rs.40 more than the compound interest compounded annually, we can set up the equation:
A₁ - A₂ = 40
P(1 + r/n)^(nt) - P(1 + r)^t = 40
Now let's substitute the values into the equation:
P(1 + 0.10/2)^(2*1) - P(1 + 0.10)^1 = 40
P(1 + 0.05)^2 - P(1 + 0.10) = 40
P(1.05)^2 - P(1.10) = 40
1.1025P - 1.10P = 40
0.0025P = 40
P = 40 / 0.0025
P = 16,000
Therefore, the principal sum of money is Rs. 16,000.