N(7.0, 1.25) Population Normal Distribution X0 = 5.0 Z0 = (5.0 7.0) / 1.25 = -1.6 – P -1.6) = 0.0548 (Z ≤ = 5.48 % P (Z -1.6) = 1 - 0.0548 = 0.9452 ≥ = 94.52% b) You chose three babies at random. What is the probability that their average birth weight is more than 5.0 pounds? Write out Sampling distribution N(µ, ). Locate X0 and calculate Z0 (Z-score), then given the Hint: probability that the question asked for. N(7.0, 1.25/ Sampling Mean Normal Distribution X0 = 5.0 Z0 = (5.0 7.0) / (1.25 /) = - 2.77 – P (Z -2.77) = 0.0028 ≤ = 0.28% P (Z -2.77) = 1 - 0.0028 = 0.9972 ≥ = 99.72 % Choose 5A or 5B. The average height of 18-year-old American women is 64.2 inches with standard 5A. Women’s height. deviation 2.7 inches. You wonder whether the mean height of this from your year’s female graduate local high school is shorter than the national average. You measure an SRS of 61 female graduates and find that = 63.0 inches. (20 points)
N(7.0, 1.25) Population Normal Distribution X0 = 5.0 Z0 = (5.0 – 7.0) / 1.25 = -1.6 P (Z ≤ -1.6) = 0.0548 = 5.48 % P (Z ≥ -1.6) = 1 - 0.0548 = 0.9452 = 94.52% b) You chose three babies at random. What is the probability that their average birth weight is more than 5.0 pounds? Hint: Write out Sampling distribution N(µ, ). Locate X0 and calculate Z0 (Z-score), then given the probability that the question asked for. N(7.0, 1.25/ Sampling Mean Normal Distribution X0 = 5.0 Z0 = (5.0 – 7.0) / (1.25 /) = - 2.77 P (Z ≤ -2.77) = 0.0028 = 0.28% P (Z ≥ -2.77) = 1 - 0.0028 = 0.9972 = 99.72 % Choose 5A or 5B. 5A. Women’s height. The average height of 18-year-old American women is 64.2 inches with standard deviation 2.7 inches. You wonder whether the mean height of this year’s female graduate from your local high school is shorter than the national average. You measure an SRS of 61 female graduates and find that = 63.0 inches. (20 points)
Exam-2-answer-Spr.14.docx