The 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 108 hours. A random sample of 81 light bulbs indicated a sample mean a life of 370 hours. 1. The 95% confidence interval estimate is from a lower limit of hours to an upper limit of hours. 2. Do you think that the manufacturer has the right to state that the lightbulbs have a mean life of 420 hours? Explain. Based on the sample data, the manufacturerA the right to state that the lightbulbs have a mean life of 420 hours. A mean of 420 hours is B standard errors C the sample means, so it is D that the lightbulbs have a mean life of 420 hours. A: does not have or has B: more than 4 or less than 2 C: above or below D: likely or highly unlikely 3. Must you assume that the population light bulb life is normally distributed? Explain. Either A-D A. No, since σ is known, the sampling distribution of the mean does not need to be approximately normally distributed. B. Yes, the sample size is too large for the sampling distribution of the mean to be approximately normal by the Central Limit Theorem. C. No, since σ is known and the sample size is large enough, the sampling distribution of the mean is approximately normal by the Central Limit Theorem. D. Yes, the sample size is not large enough for the sampling distribution of the mean to be approximately normal by the Central Limit Theorem.

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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The 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 108 hours. A random sample of 81 light bulbs indicated a sample mean a life of 370 hours.

1. The 95% confidence interval estimate is from a lower limit of __ hours to an upper limit of __ hours.

2. Do you think that the manufacturer has the right to state that the lightbulbs have a mean life of 420 hours? Explain.

Based on the sample data, the manufacturer__A__ the right to state that the lightbulbs have a mean life of 420 hours. A mean of 420 hours is __B__ standard errors __C__ the sample means, so it is __D__ that the lightbulbs have a mean life of 420 hours.

A: does not have or has

B: more than 4 or less than 2

C: above or below

D: likely or highly unlikely

3. Must you assume that the population light bulb life is normally distributed? Explain. Either A-D

A. No, since σ is known, the sampling distribution of the mean does not need to be approximately normally distributed.

B. Yes, the sample size is too large for the sampling distribution of the mean to be approximately normal by the Central Limit Theorem.

C. No, since σ is known and the sample size is large enough, the sampling distribution of the mean is approximately normal by the Central Limit Theorem.

D. Yes, the sample size is not large enough for the sampling distribution of the mean to be approximately normal by the Central Limit Theorem.

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