A factory manufacturing light emitting diode LED bulbs claims that their light bulbs last for 50,000 hours on the average. To confirm if this is valid, a quality control manager obtained a sample of...

Extracted text: A factory manufacturing light emitting diode LED bulbs claims that their light bulbs last for 50,000 hours on the average. To confirm if this is valid, a quality control manager obtained a sample of 50 LED light bulbs and got a mean lifespan of 40,000 hours. The standard deviation of the manufacturing process is 1000 hours.


Extracted text: 4. Construct a 95% confidence interval of the true mean life span of LED light bulbs manufactured by this factory. 5. Do you think that the claim of the manufacturer is valid? Explain. 6. If you want to be 99% confident that the point estimate is at most 100 hours from the true mean life span, how many light bulbs should be included in the sample?