1, if you put it back after each draw, the probability of drawing a white ball every time is 5/ 1 1.
2. If you don't put it back after every draw, you should judge it according to the color of the ball drawn for the first time.
① If you draw a white ball for the first time, the probability of drawing a white ball for the second time is 4/ 10.
② If you draw a black ball for the first time, the probability of drawing a white ball for the second time is 5/ 10.
③ According to the result of ①+②, if the first ball is unknown, the answer is (4/10) * (5/1)+(5/10) * (6/1/kloc-).
The answer here is very serious. I hope it will help you and get good comments.