Question

Question 4 1 pts A survey of 400 students provides a sample mean of 7.10 hours worked per week. From previous studies, the researcher knows that the standard deviation of this variable is 5 hours. What is a 95% confidence interval based on this sample? (6.10, 8.10) (6.45, 7.75) (6.61, 7.59) (7.10, 8.48)

Answer 1

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Option c). ( 6.61 , 7.59 ) is correct .

Date Doge solution: given that A survey of 600 students provides a sample mean of 7.10 hours worked per week, from previous studies the researcher knows that standard deviation of this variable is shouss. from above information, sample size=n=400 sample means X= 7-10 pop celation standard deviations = 3= 5 We want to find 95% confidence internal for population mean is, confidence level = 0.95 ² devel of significance = a = 0.05 95% confidence internal is for in is P (121 7 2 06/2) =0.95 P(-2o.ors a 7-4 s Loos) =0.95 P-1.96 X0-25 x 740-aft 1.96 x 012 X 0.25) = 0.95 p C -0.49 < 7.10.ws 0:49) -0.95 P ( 7.10 -0.49 < uc 7-10 +0.4g) 20.gs p(6.61 r 7.59) =0.95 95% confidence internal for u is (6.61, 7:59) Here, Rolpe 20.05/2 1.96 is calcwate from standard normal distoibution table