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.
Calculations of Confidence interval and sample size needed are provided. The solution is detailed and well presented.