Question

A normal population has a mean of 19 and a standard deviation of 4. Use Appendix B.3.

1. Compute the z value associated with 23. (Round your answer to 2 decimal places.)

2. What proportion of the population is between 19 and 23? (Round z-score computation to 2 decimal places and your final answer to 4 decimal places.)

3. What proportion of the population is less than 17? (Round z-score computation to 2 decimal places and your final answer to 4 decimal places.)

Answer 1

µ = 19

sd = 4

Z = (X - µ) / sd

Z score for 23 = (23 - 19) / 4 = 1

b)

                                         

                                          = P(0 < Z < 1)

                                          = P(Z < 1) - P(Z < 0)

                                          = 0.8413 - 0.5

                                          = 0.3413

c)

                            

                             = P(Z < -0.5)

                             = 0.3085