If the interest is payable annually than the principal on which the compound interest for 3 years at 10% P.a is Rs 33/- is given by:__________?

A. Rs 900
B. Rs 1000
C. Rs 1050
D. Rs 1100
Explanation:
Let the principal be Rs x.
Then X × (1 + 10/100)3 – x = 331
=> (x × 11/10 × 11/10 × 11/10 – x) = 331
=> ((1331x-1000x)/1000) = 331
=> 331x = 331000
=> X = 1000
Hence the principal is Rs 1000