Question

5. A hospital is studying the amount of time that patients spend waiting in the emergency room before they are called back to see a doctor. A committee conducts a random survey of 65 emer- gency room patients. The sample mean is 1.6 hours with a sample standard deviation of 0.45 hours. (a) Use your calculator to find a 90% confidence interval for the population mean time spent waiting. Briefly explain what keys you used. (b) What is the error bound (EBM) for the confidence interval you just found? (c) Explain in complete sentences what the confidence interval means.

Answer 1

= 0.05 As Given n = 65 Mean (X) =1:6 S = 0.45 Confidence interwal = 0.90 d = 1-0.90 -0.1 ala (o) population standard deviation is unknown to will use t- table distribution. (of - n-1= 65-1364) tortical = tala rdf = toog 164 = $1.669 ( Using t-tabole) 90% confidence intervalo a) u = X t trila idf * S = 1.6+ 1.669 *0.45 165 = 1.6 E 0.0932 = 1.5068 , 1.6932 2 a 11.507 1.693 6) Evrou bound - E = tolla idf *s E = 1.669 * 0.45 565 E - 0.0932 a 10.093 c) We are 90% confident that the population population mean Uime spent waiting between 11.5017 to 1.693