Discussion:
Q: A company manufactures steel bolts that continuously feed an assembly line downstream. Historically, the thickness of these bolts follows a normal distribution with a standard deviation of 1.6 mm. A recent random sample of 10 observations yielded these values of thickness, in mm:
|
9.7
|
9.9
|
10.3
|
10.1
|
10.5
|
|
9.4
|
9.9
|
10.1
|
9.7
|
10.3
|
a. Construct a 95% confidence interval for the true mean thickness.
b. Find the number of observations, n, required to estimate the true mean thickness to within ±0.2 mm using a 95% confidence interval.