Amar, Bittu and Chandan started a business with their investment in the ratio 3 : 6 : 4. After 8 months, Amar again invested the same amount as before. Bittu and Chandan withdraw half of their investment. What is the ratio of their profit at the end of the year?
1
5 : 6 : 10
2
12 : 10 : 9
3
12 : 15 : 10
4
10 : 12 : 15
5
None of these