Find the mean statistics

Question

If 5 % of caculators are defective find the mean(Expectation), variance and standard deviation of a
lot of 25 Calculators.

Answer 1

n=25

p =.05

mean = np = 1.25

variance = npq = 1.25(.95) = 19/16

standard deviation = sqrVar = sqr(19/16 = .25sqr19 = about 1.09