Q1)  Which of following is valid probability value for discrete random variable? 

a) 0.22

b) 1.01

c) -.75

d) All of the above

e) None of the above

Q2) The J.O. Supplies Company purchases calculators from Korean supplier. Probability of defective calculator is 10%. If 15 calculators are chosen at random, determine the probability that 3 or more of calculators will be defective? 

Q3) Of all individual tax returns, 37% include errors made by taxpayer. If IRS examiners are allotted randomly selected returns in batches of 12, determine mean and standard deviation for number of erroneous returns per batch. 

a) µ=2.80, σ=1.67

b) µ =4.44, σ =1.67

c) µ =4.44, σ =2.80

d) µ =2.80, σ =2.10

Q4) Assume that airplane engine will fail, when in flight, with probability 1-p independently from engine to engine; assume that airplane will make a successful flight if at least 50% of its engines remain operative. For what values of p four-engine plane is preferable to two-engine plane? Describe your selection for probability distribution.