A person deposits Rs. 500 for 2 years, Rs. 600 for 5 years and Rs. 1000 for 6 years at the same rate of simple interest. If he receives a total interest of Rs. 1000, then what is the rate of interest per year?

For simple interest: SI = Principal × Time × Rate/100. Total interest = (500×2×r + 600×5×r + 1000×6×r)/100 = (1000r + 3000r + 6000r)/100 = 10000r/100 = 100r = 1000. Therefore r = 10% per year. This problem tests the ability to handle multiple simple interest calculations simultaneously and sum them to find the unknown rate. Each deposit earns interest independently at the same rate.