A sum was put at simple interest at a certain rate for 10 years . Had it been put at 5% higher rate , it would have fetched Rs.400 more. What was the Sum?	Choose the correct choice from the following options
A) s . 1200 B) s . 800 C) s . 1400 D) s . 1000 E) s . 920

Rationale: "at 5 % more rate , the increase in s . i for 10 years = rs . 400 ( given ) so , at 5 % more rate , the increase in si for 1 year = 400 / 10 = rs . 40 / - i . e . rs . 40 is 5 % of the invested sum so , 1 % of the invested sum = 40 / 5 therefore , the invested sum = 40 × 100 / 5 = rs . 800 answer : b"
Answer: B