(b) The average operating life of light bulbs produced by Company A is 8100 hours and a standard deviation of 400 hours. Company B produces similar light bulbs with mean operating life of 8200 hours...

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Extracted text: (b) The average operating life of light bulbs produced by Company A is 8100 hours and a standard deviation of 400 hours. Company B produces similar light bulbs with mean operating life of 8200 hours and standard deviation of 480 hours. It is known that the populations are normally distributed. You are given 60 samples from Company A and 80 samples from Company B. Analyze the situation and compute the probability that sample light bulbs from Company A will have mean operating life of at most 50 hours more than the sample mean operating life from Company B.