A and B invests Rs.3500 and Rs.4000 respectively in a business. If A doubles his capital after 6 months. In what ratio should A and B divide that year's profit? Pick.
A) 21 : 5 B) 21 : 16 C) 21 : 2 D) 9 : 9 E) 21 : 11

Rationale: "( 3.5 * 6 + 7 * 6 ) : ( 4 * 12 ) 63 : 48 = > 21 : 16 answer : b"
Answer: B