Question

For certain software, independently of other users, the probability is 0.07 that a user encounters a fault. What are the chances of the 30th user is the 5th person encountering a fault?

Answer 1

Let p denote the probability that a user encounters a fault. Thus, p = 0.07

Now, we need to find the probability that the 30th user is the 5th person encountering a fault. We can break this event into two independent events namely, "4 out of first 29 users encounter a fault" and "the 30th user encounters a fault"

Now, the probability that 4 out of first 29 users encounter a fault is given by:

[Using the Binomial probability of r successes in n trials : ]

Also, the probability that the 30th user encounters a fault is given by: p

Thus, the probability that the 30th user is the 5th person encountering a fault is given by:

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