A sum of money at simple interest amounts to Rs. 805 in 3 years and to Rs. 854 in 4 years. The sum is:	Choose the correct choice from the following:	A) s. 650	B) s. 690	C) s. 688	D) s. 700	E) s. 718
S.I. for 1 year = Rs. (854 - 815) = Rs. 39.   S.I. for 3 years = Rs.(39 x 3) = Rs. 117.   Principal = Rs. (805 - 117) = Rs. 688.   Answer: Option s. 688
<result>C</result>
A sum of money at simple interest amounts to Rs. 805 in 3 years and to Rs. 854 in 4 years. The sum is: