Mother deposited 4000 yuan in the bank for two years, with an annual interest rate of 2.43%. How much principal and interest can mom get after the expiration?

(2)

Xiaoying deposited her lucky money, 300 yuan, in the bank, ready to help out-of-school children in poverty-stricken areas. She has a one-year fixed deposit with an interest rate of 2.25%. How much can Xiaoying donate to poor areas after the expiration?

(3)

Li Mingjia bought 5,000 yuan of national construction bonds with a fixed term of 3 years and an annual interest rate of 3.9%. How much principal and interest can he get at maturity?

(4)

On May 1 day, 2003, Li Xiaodong deposited the accumulated RMB 500 yuan in the credit union, with a term of 3 years. If the annual interest rate is 2.52%, how much principal and after-tax interest can you get at maturity?

(5)

Teacher Wang deposited 20,000 yuan in the bank, 1 year, with pre-tax interest and principal of * * * 20,450 yuan after maturity. What is the annual interest rate？

(6)

The annual interest rate of the two-year time deposit is 2.7%, and Li Shifu has 2,000 yuan in the bank. How much after-tax interest can he get back at maturity? (Interest tax is 20%)