Suppose random variable X follows a normal distribution with mean = 181 units. Further, we are given that P(X < 234) = 0.9452. The standard deviation of X is:

a. 37.9

b. 41.4

c. 33.1

d. 26.5

A certain famous Canadian tennis player makes a successful first serve 66% of the time. Assume that each serve is independent of the others. If she serves 4 times, what is the probability that exactly 2 of these first serves will be in?

a. 0.3021

b. 0.4193

c. 0.6979

d. 0.5807

Consider two random events A and B. Event A^cis the complement of event A, and B^cis the complement of B. P(A) =0.67. P(B) = 0.21, and P(A and B) =0.1548.Using a joint probability table, or otherwise, findP(B^c|A^c)

a. 0.8327

b. 0.3478

c. 0.769

d. 0.1673