ts (a) through (d) below. Construct a 95% confidence interval estimate for the population mean life of light bulbs in this shipment. from a lower limit of 342.6 hours to an upper limit of 397.4 hours. e 95% confidence interval estimate pund to one decimal place as needed.) Do you think that the manufacturer has the right to state that the lightbulbs have a mean life of 420 hours? Explain. sed on the sample data, the manufacturer does not have the right to state that the lightbulbs have lightbulbs have a mean life of 420 hours. mean life of 420 hours. A mean of 420 hours is more than 3 standard errors above the sample mean, so it is highly unlikely that Must you assume that the population light bulb life is normally distributed? Explain. A. Yes, the sample size is not large enough for the sampling distribution of the mean to be approximately normal by the Central Limit Theorem. B. No, since a is known, the sampling distribution of the mean does not need to be approximately normally distributed. C. Yes, the sample size is too large for the sampling distribution of the mean to be approximately normal by the Central Limit Theorem. D. No, since o is known and the sample size large enough, the sampling distribution of the mean is approximately normal by the Central Limit Theorem. Suppose the standard deviation changes to 77 hours. What are your answers in (a) and (b)? e 95% confidence interval estimate would be from a lower limit of hours to an upper limit of hours. ound to one decimal place as needed.) sed on the sample data and a standard deviation of 77 hours, the manufacturer the right to state that the lightbulbs have a mean life of 420 hours. A mean of 420 hours is v standard errors V the sample ean, so it is V that the lightbulbs have a mean life of 420 hours.