In a certain population, 20% of the people have minor eye defect. A sample of 100 people is

selected at random from this population.

a. The mean number of people with minor eye defect in the sample is ________________.

The standard deviation of the number of people with minor eye defect in the sample is

_____________________

b. If you use normal approximation to binomial and take continuity correction factor into

account, then probability that 25 or less people (at most 25 people) in the sample have

minor eye defect is

___________