Consider the data in Exercise 1 on the time (in minutes) to process hot-rolled steel for a sample of size 10.
(a) Find a 98% confidence interval for the mean time to process hot-rolled steel. What assumptions do you have to make to solve this problem?
(b) Find a 95% confidence interval for the variance.
(c) Test the hypothesis that the process variability, as measured by the variance, exceeds 0.80. Use α ˆ 0.05.
Exercise
The following times(in minutes) to process hot-rolled steel are observed for a random sample of size 10:
5.4 6.2 7.9 4.8 7.5
6.2 5.5 4.5 7.2 6.2
(a) Find the mean, median, and mode of the processing times. Interpret the differences between them.
(b) Compute the range, variance, and standard deviation of the processing times and interpret them.