Xiao Ming deposits 1000 yuan in the bank and takes out 500 yuan to donate to the disaster area one year later. Then he deposits the remaining 500 yuan and the due interest one year at a fixed time. If the annual interest rate of the deposit remains unchanged, he can take out 660 yuan in the later period and ask for the annual interest rate

Xiao Ming deposits 1000 yuan in the bank and takes out 500 yuan to donate to the disaster area one year later. Then he deposits the remaining 500 yuan and the due interest one year at a fixed time. If the annual interest rate of the deposit remains unchanged, he can take out 660 yuan in the later period and ask for the annual interest rate

Let the annual interest rate be X. according to the meaning of the question, we can get: 1000 (1 + x) - 500] (1 + x) = 660. The solution is: X1 = 0.1, X2 = - 1.5. Answer: the annual interest rate is 10%