Using the output in Exercise 9: a. Find the critical value z2 for a 99% confidence interval. b. Use the critical value along with the

Using the output in Exercise 9:

a. Find the critical value zα∕2 for a 99% confidence interval.

b. Use the critical value along with the information in the output to construct a 99%

confidence interval for the mean reading of the scale.

Exercise 9

To estimate the accuracy of a laboratory scale, a weight known to have a mass of 100 grams is weighed 32 times. The reading of the scale is recorded each time. The following MINITAB output presents a 95% confidence interval for the mean reading of the scale.

A scientist claims that the mean reading μ is actually 100 grams. Is it likely that this claim is true?

The assumed sigma Variable Scale Reading = 2.5000 N Mean 32 102.3527 StDev 2.5000 SE Mean 0.44194 95% CI (101.4865, 103.2189)