A invested Rs.10000 in a business. After some months, B joined the business with an investment of Rs.8000. At the end of the year, the profit share of B is Rs.7000 out of the total profit of Rs.22000. Find B joined after how many months?

Correct option is B

Let B joined after ‘x’ months
Profit sharing ratio of A to B = (10000×12) : (12-x)×8000
= 15:(12-x)
ATQ,
$$\frac{15}{12 - x} = \frac{22000 - 7000}{7000}$$​
7 = 12 - x
x = 5