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For a random sample of 10 light bulbs, the mean bulb life is 4,000 hr with...

For a random sample of 10 light bulbs, the mean bulb life is 4,000 hr with a sample standard deviation 200. For another brand of bulbs, a random sample of 8 has a sample mean of 4,300 hr and a sample standard deviation of 250. Assume that the life of a light bulb is normally distributed and the standard deviations of the two populations are equal. We test the hypothesis that there is no difference between the mean operating life of the two brands of bulbs, using the 1 % level of significance.

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TOPIC:Two sample t-test for the population means.

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