A quality-control manager wants to test whether there is any difference in the length of life of three brands of light bulbs. Random samples of new light bulbs installed in the firm's office light fixtures yield the expiration data (in hours) in the following table. The data are also available on the text website, labeled Bulb Longevity.
a. Specify the competing hypotheses in order to test whether differences exist in the median length of life of the three brands of light bulbs.
b. Calculate the value of the test statistic H.
c. Approximate the p-value.
d. At the 10% significance level, do differences exist between the median length of life of the three brands? Explain.