Question

Suppose the lengths of the pregnancies of a certain animal are approximately normally distributed with mean u=266 and standard deviation 26 days. (a) what is the probability that a randomly selected pregnancy lasts less than 256 days? (b) what is the probability that a random sample of 16 preganacies has a mean geatation period of 256 days or less? (c) what is the probability that a random sample of 37 preganacies has a mean geatation period of 256 days or less? MUST SHOW WORK

Answer 1

µ = 266

sd = 26

a)

                               

                                = P(Z < -0.38)

                                = 0.3520

b) n = 16

                           

                            = P(Z < -1.54)

                            = 0.0618

c) n = 37

                           

                            = P(Z < -2.34)

                            = 0.0096