H 138 Exam 3A Name/hichael Newman pring 2018 / meral Directions: You may use a c
ID: 2908828 • Letter: H
Question
H 138 Exam 3A Name/hichael Newman pring 2018 / meral Directions: You may use a calculatoand a 4-x 6. index card Please show your work to receive full credit. When you use the calculator, write down the commands that you entered, so it is known what you did. Whenever you conditions and put checks next to them; briefly explain why each condition/assumption is met (or not) areasked to check conditions or assumptions, do not just list the include a diagram where appropriate. (Numbers in parentheses are the point value of the problem.) (5 points)Problem 1: One television poll stated that the recent approval rating of a politician was 72% with a margin of error of 3% at a 95% confidence level. What is the required sample size to meet these requirements? ,0345 (6 points)Problem 2: The engines made by Ford for speedboats had an average power of 220 horsepower (HP) and standard deviation of 15 HP. A potential buyer intends to take a sample of four engines and will not place an order if the sample mean is less than 215 HP. What is the probability that the buyer will not place an order? Include a diágram to support your answer. Round all answers to four decimal places 220Explanation / Answer
Solution:-
1. Given that p = 0.72, q = 0.28, ME = 0.03, 95% confidence interval for Z = 1.96
n = (Z/E)^2*p*q
= (1.96/0.03)^2*0.72*0.28
= 860.5184
= 861
2. Given that mean = 220, sd = 15, n = 4, x = 215
=> P(X < 215) = P(Z < (215-220)/15/sqrt(4))
= P(Z < -0.1667)
= 0.4325
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