First, consider the situation that six balls are randomly taken from 10 and not put back.
The first ball has 10 moves, the second ball has 9 moves and the sixth ball has 5 moves. So six balls were randomly selected from 10 balls. There are five ways to get it:/kloc-0 10X9X8X7X6X5.
Then consider the case where the X-ball is not taken.
If the X-ball is not taken out, it means that the six balls taken out are all taken out from nine balls other than the X-ball. The first ball has nine moves, the second ball has eight moves and the sixth ball has four moves. Therefore, six balls are randomly selected from the nine balls other than the X ball-* * * There are four ways to take them.
It can be seen from the above that the probability of taking out six balls from 10 without putting them back at will and not taking the X ball is (9x87x6x5x4)/(10x9x87x5) = 0.4.
So the probability that the X-ball is taken away is 0.6.