Among companies doing highway or bridge construction, 80% test employees for substance abuse (based upon data from Construction Financial Management Association) A study involves random selection of 12 such companies.
(a) Determine the probability that exactly 7 of 12 companies test for substance abuse.
(b) Determine the probability that at least half of companies test for substance abuse.
(c) For such group of 12 companies, Determine the mean and standard deviation for number (among 12) that test for substance abuse.
(d) Using the results from part (c) and range rule of thumb, Determine the range of usual value