P invests Rs. 500, Q invests some amount and R invests Rs. 400 into a partnership. After 8 months, P and Q added Rs. 200 to their investments. After a year, 10% of profit goes for Orphanage and Remaining is distributed into three. If total profit is of Rs. 3920 And profit share of Q is Rs. 1440 then find the initial investment of Q.