Solved: The life in hours of a 75-watt light bulb is known to be normally distributed
Chapter 8, Problem 8-12(choose chapter or problem)
The life in hours of a 75-watt light bulb is known to be normally distributed with 25 hours. A random sample of 20 bulbs has a mean life of hours. (a) Construct a 95% two-sided confidence interval on the mean life. (b) Construct a 95% lower-confidence bound on the mean life.
Unfortunately, we don't have that question answered yet. But you can get it answered in just 5 hours by Logging in or Becoming a subscriber.
Becoming a subscriber
Or look for another answer