Question

A package of light bulbs promises an average life of more than 750 hours per bulb....

A package of light bulbs promises an average life of more than 750 hours per bulb. A consumer group did not believe the claim and tested a sample of 40 bulbs. The average lifetime of these 40 bulbs was 740 hours with ? = 30hours. The manufacturer responded that its claim was based on testing hundreds of bulbs.

b.Given the usual sampling assumptions, is there a 95% probability that 750 lies in the 95% confidence interval of the manufacturer?

c.If the manufacturer’s confidence interval more likely to contain the population mean because it is based on a larger sample?

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