Question

A manufacturer produces piston rings for an automobile engine. It is known that ring diameter is Normally Distributed with ? = 0.001 ??. A random sample of 9 rings has a mean diameter of ? = 74.036 ??

a. What is a 95% ?????????? ???????? for the true mean diameter of the piston rings. Use the given ? = 0.001 ??.

b. Interpret the ?????????? ???????? constructed in part (a)

c. For mathematical purposes, assume for a moment that the given standard deviation is the sample standard deviation, ? = 0.001. Construct a new 95% ?????????? ???????? using the sample standard deviation.

d. Compare your answers in (a) and (c), and explain why do you agree or disagree with the statement: “the ? ?????????? ????????? are wider than the ? ?????????? ?????????”.

e. The standard deviation calculated for the sample was found to be, ? = 0.0025. Use the calculated sample standard deviation and construct a new 95% ?????????? ????????.

Answer 1

A.

B.

C.

D.

I agree because critical values for t-intervals are bigger which makes the margin of error bigger and hence wider confidence intervals.

E.

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