The qualty control manager at a light bulb tactory needs to estimate the mean Ir

Question

The qualty control manager at a light bulb tactory needs to estimate the mean Ire of alarge shipment of Mght bulbs bulbs indicated a sample mean Ite of 300 hours. Complete parts (a) through (d) below. a. Construct a 95% confidence interval estimate for the population mean life of light bulbs in this shipment. The 95% 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 manutacturer hasthe nght to state that the lghtbults have a mean are of 350 hours? Explain Based on the sample data, the manutacturer the right to state that the lightbulbs have a mean ire of 350 hours A mean of 350 hours is errors the sample mean, so it is that the lightbulbs have a mean Ife of 350 hours C. Must you assume that the population light bulb life is normally distributed? Explain O A. No, since o is known and the sample size is large enough, the sampling distribution of the mean is approximately normalby the central Limt Theorem Click to select your answer(s)

Explanation / Answer

Here, S = 84 hrs , mean = 300, n= 49

SE = s / sqrt(n) = 84 / sqrt(49) = 12

for 95% CI z value = 1.645

CI = mean + / - Z * SE

= 300 + / - 1.645 * 12

= (280.26 , 319 . 74)

a) Lower limit of 280.26 hours and upper limit of 319.74 hours

d) Std. deviation = 63 hours

SE = s/ sqrt(n) = 63 / sqrt(49) = 9

CI = mean + / - Z * SE

= 300 + / - 1.645 * 9

= (285.19 , 314.80)

Lower limit of 285.19 hours and upper limit of 314.80 hours

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