Investment in mutual funds through systematic investment plans dropped to a 31-month low of Rs 7,302 crore in November amid challenging economic environment. However, investment through the Systematic Investment Plans (SIPs) route had risen in October after six months of continuous decline.The 44-player mutual fund industry witnessed an inflow to the tune of Rs 7,302 crore through SIPs in November as compared to Rs 7,800 crore in the preceding month.