The lifetime (in hours)of a 60-watt light bulb is a random variable that has a Normal distribution with $\sigma$ = 30 hours.A random sample of 25 bulbs put on test produced a sample mean lifetime of = 1038.Construct a 92% confidence interval estimate for the mean lifetime $\mu$.If it were desired to cut the confidence interval to half its length while keeping the same 92% level,what size sample would be required to achieve this?
A)50
B)13
C)75
D)100
E)41

Question

The lifetime (in hours)of a 60-watt light bulb is a random variable that has a Normal distribution with $\sigma$ = 30 hours.A random sample of 25 bulbs put on test produced a sample mean lifetime of  = 1038.Construct a 92% confidence interval estimate for the mean lifetime $\mu$.If it were desired to cut the confidence interval to half its length while keeping the same 92% level,what size sample would be required to achieve this?
A)50 
B)13 
C)75 
D)100 
E)41

Quizplus · Accepted Answer

The Answer of The lifetime (in hours)of a 60-watt light bulb is a random variable that has a Normal distribution with $\sigma$ = 30 hours.A random sample of 25 bulbs put on test produced a sample mean lifetime of  = 1038.Construct a 92% confidence interval estimate for the mean lifetime $\mu$.If it were desired to cut the confidence interval to half its length while keeping the same 92% level,what size sample would be required to achieve this?
A)50 
B)13 
C)75 
D)100 
E)41

The Lifetime (In Hours)of a 60-Watt Light Bulb Is a Random