the lonco Electric company advertising that their new 90 watt Extend life light
ID: 3378914 • Letter: T
Question
the lonco Electric company advertising that their new 90 watt Extend life light bulbs have an average lifetime of 2500 hours . The consumer protection Agency tested a sample of 150 lonco 90 watt extended life bulbs and computed the mean and standard deviation as 2460 and 201 hours respectively . Comput a 95% confidence interval for the average lifetime of all Lonco extended life 90 watt light bulbs , and then say if the consumer protection Agency found the Lonco Electric Company in or out of compliance with the Fair Advertising Act.
Explanation / Answer
CI = x ± t a/2 * (sd/ Sqrt(n))
Where,
x = Mean
sd = Standard Deviation
a = 1 - (Confidence Level/100)
ta/2 = t-table value
CI = Confidence Interval
Mean(x)=2460
Standard deviation( sd )=201
Sample Size(n)=150
Confidence Interval = [ 2460 ± t a/2 ( 201/ Sqrt ( 150) ) ]
= [ 2460 - 1.976 * (16.412) , 2460 + 1.976 * (16.412) ]
= [ 2427.571, 2492.429 ]
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.