Consider a Binomial random variable X with expected value E(X) = 20, and standrad deviation = 3.16. The approximate value for P(X = 19), using Normal approximation to Binomial, is:

a. 0.12

b. 0

c. 0.237

d 0.072

In Melanie's Styling Salon, the time to complete a simple haircut is normally distributed with a mean of 28 minutes and a standard deviation of 8 minutes. On a normal Monday afternoon, two random customers walked into Melanie s and both asked for a simple haircut. Let X represent the total time to complete the haircuts for these two customers. What is the standard deviation of X?

a. 16

b. 11.31

c. 128

d. 5.66

A large number of applicants for admission to graduate studies in business are given an aptitude test with a resulting mean score of 440 and a standard deviation of 90. The scores are known to follow a normal distribution. What fraction of the applicants would you expect to have a score of 350 or more?

a. 0.159

b. 0.579

c. 0.421

d. 0.841