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A machine produces metal rods used in an automobile
Chapter 8, Problem 40E(choose chapter or problem)
A machine produces metal rods used in an auto-mobile suspension system. A random sample of 15 rods is selected, and the diameter is measured. The resulting data (in millimeters) are as follows:
8.24 8.25 8.20 8.23 8.24
8.21 8.26 8.26 8.20 8.25
8.23 8.23 8.19 8.28 8.24
(a) Check the assumption of normality for rod diameter.
(b) Calculate a 95% two-sided confidence interval on mean rod diameter.
(c) Calculate a 95% upper confidence bound on the mean. Compare this bound with the upper bound of the two-sided confidence interval and discuss why they are different.
Questions & Answers
QUESTION:
A machine produces metal rods used in an auto-mobile suspension system. A random sample of 15 rods is selected, and the diameter is measured. The resulting data (in millimeters) are as follows:
8.24 8.25 8.20 8.23 8.24
8.21 8.26 8.26 8.20 8.25
8.23 8.23 8.19 8.28 8.24
(a) Check the assumption of normality for rod diameter.
(b) Calculate a 95% two-sided confidence interval on mean rod diameter.
(c) Calculate a 95% upper confidence bound on the mean. Compare this bound with the upper bound of the two-sided confidence interval and discuss why they are different.
ANSWER:Step 1 of 5
(a)
To check whether the normality for rod diameter. We need to construct a normal probability plot. If the points in the probability plot form a line or lie closer to the line drawn approximately between the 25th and 75th percentile points, then we can say that the data is normally distributed.