Probability of relatively independent events in Mathematics There are 10 balls from No.0 to No.9, which are pulled out one at a time and then put back. The probability of pulling 1 is 1 / 10, that is to say, there will be one in 10 times. Then I want to know the probability of pulling 1 only after 20 times and how much is it after 30 times

Probability of relatively independent events in Mathematics There are 10 balls from No.0 to No.9, which are pulled out one at a time and then put back. The probability of pulling 1 is 1 / 10, that is to say, there will be one in 10 times. Then I want to know the probability of pulling 1 only after 20 times and how much is it after 30 times

20 times 1 / 10 * (9 / 10) ^ 19 times 30 times 1 / 10 * (9 / 10) ^ 29