Question 1194137: A company claims that the average lifetime of a bulb that they sell is at least 36,000 hours. To check the claim, 28 bulbs were sampled and found to have mean lifetime of 32,940 hours. With a standard deviation of 1,950 hours, is the claim true?
what is the problem that is being addressed by the experimental study?
state the hypothesis base on the data and the given problem.
make a complete test of the null hypothesis so that you can give the answer to the research problem
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! assumed population mean = 36000
sample mean = 32940
population standard deviation = 1950
sample size = 28
standard error = 1950/sqrt(28) = 368.52
z-score= (32940 - 36000) / 368.52 = -8.30
the probability of getting a z-score less than or equal to -8.30 by random chance = 0.
this suggests that the average lifetime of the bulbs is more then likely less than 36000.
at 0.5% significance level, the critical z-score would be equal to -2.57
-8.30 is much greater than that.
this supports the conclusion that the average lifetime of the bulbs is more than likely less than 36000 hours.
the standard error represents the standard deviation of the distribution of a large number of sample means from samples that all have 28 elements in them.
let me know if you have any questions.
theo
|
|
|
