Simple interest on a certain sum of money for 3 years at 8% per annum is half the compound interest on Rs. 4000 for 2 years at 10% per annum. The sum placed on simple interest is  Select the correct option:
A) rs 1650 B) rs 1750 C) rs 1850 D) rs 1950 E) none of these

Rationale: "explanation : c . i . = ( 4000 × ( 1 + 10 / 100 ) 2 − 4000 ) = 4000 ∗ 11 / 10 ∗ 11 / 10 − 4000 = 840 so s . i . = 840 / 2 = 420 so sum = s . i . ∗ 100 / r ∗ t = 420 ∗ 100 / 3 ∗ 8 = rs 1750 option b"
Answer: B