The simple interest on a sum of money will be Rs. 600 after 10 years.If the principal is trebled after 5 years,what will be the total interest at the end of the tenth year ?	Select the correct option.
A) rs . 600 B) rs . 900 C) 1200 rupees D) rs . 1500 E) none

Rationale: solution 22.22 let the sum be rs . x . now , s . i . = rs . 600 , t = 10 years . rate = % = ( 100 x 600 / x x 10 ) % = ( 6000 / x ) % s . i . for first 5 years = rs . ( x x 5 x 6000 / x x 100 ) = rs . 300 . s . i . for first 5 years = rs . ( 3 x x 5 x 6000 / x x 100 ) = rs . 900 . ∴ total interest = rs . 1200 . answer c
Answer: C