Three brands of flashlight batteries are to be compared by testing each brand in 4 flashlights. Twelve flashlights are randomly selected and divided randomly into three groups of four flashlights each. Then each group of flashlights uses a different brand of battery. The lifetimes of the batteries, to the nearest hour, are as follows.

Brand A	Brand B	Brand C
16	15	15
17	15	14
13	13	13
18	17	14

Preliminary data analyses indicate that the independent samples come from normal populations with equal standard deviations. At the 5% significance level, does there appear to be a difference in mean lifetime among the three brands of batteries?