Present value, P = Rs.40960
Interest rate, R = (25/2)% per annum
Time, n = 3/2 years
∵ Compounded half-yearly.
∴ Amount (A) = P [1 + (R/2)/100]2n [Where, P = Present value
R = Annual interest rate
n = Time in years]
∴ A = 40960 [1 + (25/4)/100]3 [R = 25/2 and n = 3/2 years]
⇒ A = 40960 [1 + 1/16]3
⇒ A = 40960 [17/16]3
⇒ A = 40960 × 4913/4096
⇒ A = 10 × 4913
⇒ A = 49130
∴ Amount = Rs.49130
∴ Compound interest = Rs.(49130 – 40960) [∵CI = A – P]
= Rs.8170