The difference between the compound interest on a sum of Rs. 8,000 for 1 year at the rate of 10% per annum, interest compounded yearly and half yearly is:

Answer: Option A

Principal = Rs. 8000
Rate = 10% p.a. = 5% half per yearly
Time = 1 year
Compound interest yearly = $$\frac{1}{10}$$ = Rs. 800
10 unit ⟶ Rs. 8000
1 unit ⟶ Rs. 800
Compound interest half yearly = $$\frac{1}{20}$$
400 unit ⟶ 8000
1 unit ⟶ 20
41 unit ⟶ 20 × 41 = Rs. 820

Difference = 820 - 800 = Rs. 20