[Emergency Help] Random variables and their distribution in high school mathematics. What's the difference between putting it back and not putting it back when calculating probability? What are the di

[Emergency Help] Random variables and their distribution in high school mathematics. What's the difference between putting it back and not putting it back when calculating probability? What are the different methods? ... For example, there are seven white balls and three black balls.

The drawing method of putting back: the probability of drawing the white ball is 0.7, and the probability of drawing the black ball is 0.3.

Drawing method without putting it back: the probability of drawing a white ball for the first time is 0.7, and the probability of drawing a black ball is 0.3.

The probability of drawing a white ball for the second time depends on what ball is drawn for the first time, and the denominator becomes 9.