Save 4000 yuan every year for 10 years, and then withdraw 4000 yuan every year for 1 10 years. How much money is left in the account in the 20th year? (interest rate is 5%)

Solution: If every 4,000 yuan is regarded as a set, there is/10 4000 yuan. It is believed that the 4000 yuan deposited in 1 year will be withdrawn in1year, and the 4000 yuan deposited in the next year will be withdrawn in1year ... In essence, this 4000 yuan was deposited in1year, and saved in1year.

10× (4000×10× 5%) = 20000 (this is a simple interest calculation).

If it is a compound interest calculation, it is much more complicated and has not been clarified.