Chapter 14.4, Problem 6Q

A sample of ten 40-W light bulbs was taken from each of three manufacturing plants. The bulbs were burned until failure. The number of hours that each remained lit is listed in the following table.

Plant 1	Plant 2	Plant 3
905	1109	571
1018	1155	1346
905	835	292
886	1152	825
958	1036	676
1056	926	541
904	1029	818
856	1040	90
1070	959	2246
1006	996	104

• (a) Test the hypothesis that the median lives of bulbs produced at the three plants are all the same. Use the 0.05 level of significance.

• (b) Are the mean lives of bulbs produced at the three plants all the same? Use the analysis of variance with $a=\mathrm{0.05.}$

• (c) Change the observation “2246” in the third column to “1500” and redo part (a). How does this change affect the hypothesis test?

• (d) Change the observation “2246” in the third column to “1500” and redo part (b). How does this change affect the hypothesis test?