A machine produces metal rods used in an automobile suspension system. A random of 18 rods is selected, and the diameter is measured.
The resulting data are shown below.
18.24 18.23 18.20
18.21 18.20 18.28
18.23 18.26 18.24
18.25 18.19 18.25
18.25 18.19 18.25
18.26 18.23 18.24
a. Is there strong evidence to indicate that mean rod diameter exceed 18.20? Use !=0.01
b. Find the P-value for the statistical test in (a)
c. Find a 95% two-sided confidence interval on mean rod diameter.