he quality control manager at a light bulb factory needs to estimate the mean life of a large shipment of light bulbs. T

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He Quality Control Manager At A Light Bulb Factory Needs To Estimate The Mean Life Of A Large Shipment Of Light Bulbs T 1 (27.54 KiB) Viewed 57 times

he quality control manager at a light bulb factory needs to estimate the mean life of a large shipment of light bulbs. The standard deviation is 91 hours. A random sample of 49 light bulbs indicated a sample mean life of 280 ours. Complete parts (a) through (d) below a. Construct a 90% confidence interval estimate for the population mean life of light bulbs in this shipment. The 99% confidence interval estimate is from a lower limit of hours to an upper limit of hours (Round to one decimal place as needed) b. Do you think that the manufacturer has the right to state that the lightbulbs have a mean ife of 330 hours? Explain Based on the sample data, the manufacturer does not have the right to state that the lightbulbs have a mean life of 330 hours. A mean of 330 hours is more than 3 standard errors above the sample mean, so it is highly unlikely that the lightbulbs have a mean ite of 330 hours e. Must you assume that the population light bulb Me is normally distributed? Explain A. No, since e is known and the sample size is large enough, the sampling distribution of the mean is approximately normal by the Central Limit Theorem OR. Yes the sample size is too large for the sampling distribution of the mean to be approximately normal by the Central Limit Theorem OC Yes the sample size is not large enough for the samping distribution of the mean to be approximately normal by the Central Limit Theorem OD No, since is known the samping distribution of the mean does not need to be approximately normally distributed d. Suppose the standard deviation changes to 77 hours. What are your answers in (a) and (b) The 99% confidence interval estimate would te tom a lower limit of hours to an upper of hours (Round to one decimal place as needed)