QUESTION 7 The life in hours of a 75-watt light bulb is known to be normally distributed with standard deviation of 25 h

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QUESTION 7 The life in hours of a 75-watt light bulb is known to be normally distributed with standard deviation of 25 h

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Question 7 The Life In Hours Of A 75 Watt Light Bulb Is Known To Be Normally Distributed With Standard Deviation Of 25 H 1
Question 7 The Life In Hours Of A 75 Watt Light Bulb Is Known To Be Normally Distributed With Standard Deviation Of 25 H 1 (34.93 KiB) Viewed 71 times
QUESTION 7 The life in hours of a 75-watt light bulb is known to be normally distributed with standard deviation of 25 hours. A random sample of 20 bulbs was selected and gave a mean life time of 1014 hours. 1. Construct a 95% confidence interval on the mean life time 2. Suppose that we wanted the error in estimating the mean life time from the confidence interval to be five hours at the 95% level of confidence. What minimum sample size should be used? 3. Suppose that you wanted the total width of the confidence interval, on the mean life time, to be six hours at the 95% level of confidence, then what is the minimum sample size should be used? 4. If the length of the CI in part 3 is to be halved, then by how much must the sample size n be multiplied?
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