A company produces the latest model of camera in large quantity. From past record, the defective rate is known to be 5%. Everyday, the company will sample a batch of 20 cameras to check for manufacturing error. Assuming that the number of defective cameras follows a binomial distribution, calculate the
1) probability of no camera is defective
2) probability that at most 2 cameras are defective
3) mean and standard deviation for the number of defective cameras