From a lot of 15 bulbs which include 5 defectives, a sample of 4 bulbs is drawn one by one with replacement. Find the probability distribution of a number of defective bulbs. Hence, find the mean of the distribution.
Out of 15 bulbs, five are defective.
Let p = probability that drawn bulb is defective
Also, the q = probability that drawn bulb is not defective.
Let X be the probability that the drawn bulb is defective out of 4.
Then, X follows a binomial distribution with,
The required binomial distribution is given by,
Let, X, be the random variable getting defective ball, so,