Find the principle on a certain sum of money at 5% per annum for 3 1/5 years if the amount being Rs.870?  Choose the correct choice from the following:
A) rs . 700 B) rs . 780 C) rs . 750 D) rs . 1000 E) none of these

Rationale: "explanation : 870 = p [ 1 + ( 5 * 16 / 5 ) / 100 ] p = 750 answer : option c"
Answer: C