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The life in hours of a 75-watt light bulb is known to be
Chapter 8, Problem 14E(choose chapter or problem)
The life in hours of a 75-watt light bulb is known to be normally distributed with \(\sigma=25\) hours. A random sample of 20 bulbs has a mean life of \(\bar{x}=1014\) hours.
(a) Construct a 95% two-sided confidence interval on the mean life.
(b) Construct a 95% lower-confidence bound on the mean life. Compare the lower bound of this confidence interval with the one in part (a).
Equation Transcription:
Text Transcription:
sigma^2=25
x bar=1014
Questions & Answers
QUESTION:
The life in hours of a 75-watt light bulb is known to be normally distributed with \(\sigma=25\) hours. A random sample of 20 bulbs has a mean life of \(\bar{x}=1014\) hours.
(a) Construct a 95% two-sided confidence interval on the mean life.
(b) Construct a 95% lower-confidence bound on the mean life. Compare the lower bound of this confidence interval with the one in part (a).
Equation Transcription:
Text Transcription:
sigma^2=25
x bar=1014
ANSWER:
Step 1 of 4
Given,
The standard deviation,
Sample size, n = 20.
The mean,
For a sample mean, 
