The formula is: a = f * I/[( 1+I) n- 1]
Namely: a =10000 *10%/[(1+10%) 3-1]
The result is: 302 1. 15 yuan.
It means that you only spent 9063.44 yuan and earned 936.56 yuan from the bank.
Your supplementary question is the same as the first question, but it is expanded by 10 times.
That is, just deposit 302 1 1.5 yuan every year. In the end, you earned more than 9000 yuan from the bank.
The result of building 1 is wrong. Is it still 402 1 yuan per year? I have saved enough in those three years 12063, and I still need to deposit it in the bank?