Current location - Training Enrollment Network - Mathematics courses - Math problem 20 points
Math problem 20 points
1, total * * * There are 19 left, and there is a drawing method of 19.

There are still four fakes left, and there are four methods to draw the fakes, with a probability of 4/ 19.

There are 9 balls left, and there are 9 ways to draw another ball.

There are five black balls, and there are five ways to draw black balls, with a probability of 5/9.

Therefore, the two questions are almost the same idea.