A starts a business with ₹ 4000 and B joins him after 3 months with ₹ 16000. Find the ratio of their profit at the end of year.

A's share : B's share
= Ratio of products of investment and time period of investment
= (4000 x 12) : 16000 x (12 - 3)
= 4 x 12 : 16 x 9
= 1 : 3
Note Here, the partnership is compound, in which A invested for 1 yr or 12 month and B invested 3 months later. it does mean B invested for (12 - 3) months.