The S.I. on a certain sum of money for 3 years at 8% per annum is half the C.I. on Rs. 4000 for 2 years at 10% per annum. The sum placed on S.I. is________?

A. Rs. 1550
B. Rs. 1650
C. Rs. 1750
D. Rs. 2000
Explanation:
C.I. = [4000 * (1 + 10/100)2 – 4000]
= (4000 * 11/10 * 11/10 – 4000) = Rs. 840.
Sum = (420 * 100)/(3 * 8) = Rs. 1750