Question

Suppose that a committee is studying whether or not there is waste of time in our judicial system. It is interested in the mean amount of time individuals waste at the courthouse waiting to be called for jury duty. The committee randomly surveyed 81 people who recently served as jurors. The sample mean wait time was 7 hours with a sample standard deviation of 2.3 hours. # Part (a) O Part (b) Which distribution should you use for this problem? Explain your choice. O The Student's t-distribution for 81 degrees of freedom should be used because the sample standard deviation is known. The standard normal distribution should be used because the sample standard deviation is known. O The standard normal distribution should be used because the population standard deviation is known. • The Student's t-distribution for 80 degrees of freedom should be used because we do not know the population standard deviation. Part (C) Construct a 95% confidence interval for the population mean time wasted. State the confidence interval. (Round your answers to two decimal places.) ( 7.50 X , 8.50 x ) hr You may need to use Table C to answer this question.

Answer 1

Critical value of t for df = 81 – 1 = 80 for 95% confidence interval is t= 1.990 ES 2.3 So, margin of error = * = 1.990 - = 0.51 n So, confidence interval is 7 + 0.51 (7 – 0.51,7 +0.51) = (6.49, 7.51)