If the probability of a defective bolt is 0.1 , then the mean and the standard deviation of the dist

Question

If the probability of a defective bolt is 0.1 , then the mean and the standard deviation of the distribution of bolts in a total of 400 are respectively

Professor PC Thomas Classes · Answer

Binomial distribution: mean $\mu = np = 400(0.1) = 40$. Standard deviation $\sigma = \sqrt{npq} = \sqrt{400(0.1)(0.9)} = 6$.