A. 9 Months
B. 10 Months
C. 11 Months
D. 12 Months
=> Say, Capital = Z
=> A's contribution = 1/4th of capital i.e. Z/4
=> So, B's capital = Total Capital - A's Capital = Z - Z/4 = 3Z/4
=> Say, B has invested for N months
=> Ratio of Investment = (Z/4) x 15 : (3Z/4) x N = 5 : N
=> Total profit = P
=> So, B's share in profit is 2P/3
=> Therefore, A's share = P - 2P/3 = P/3
=> Ratio of Profit = P/3 : 2P/3 = P : 2P = 1 : 2
=> Ratio of Investmment = Ratio of Profit
=> 5 : N = 1 : 2
=> N = 10
=> So, B's investment is for 10 Months