2. If you want to touch it for the second time, it means that you didn't touch it for the first time, and the probability of touching it for the second time =( 1-50%)*40%.

In the same way, if you touch it for the third time, it means that you didn't touch it for the first time and didn't touch it for the second time.

Then the probability of the third touch = (1-50%) * (1-40%) * 40%.

4. In the same way, other answers can be deduced.

I hope it helps you!