document.write( "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?\r
\n" ); document.write( "\n" ); document.write( "what is the problem that is being addressed by the experimental study?
\n" ); document.write( "state the hypothesis base on the data and the given problem.
\n" ); document.write( "make a complete test of the null hypothesis so that you can give the answer to the research problem \n" ); document.write( "
Algebra.Com's Answer #826250 by Theo(13342)\"\" \"About 
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assumed population mean = 36000
\n" ); document.write( "sample mean = 32940
\n" ); document.write( "population standard deviation = 1950
\n" ); document.write( "sample size = 28
\n" ); document.write( "standard error = 1950/sqrt(28) = 368.52
\n" ); document.write( "z-score= (32940 - 36000) / 368.52 = -8.30
\n" ); document.write( "the probability of getting a z-score less than or equal to -8.30 by random chance = 0.
\n" ); document.write( "this suggests that the average lifetime of the bulbs is more then likely less than 36000.
\n" ); document.write( "at 0.5% significance level, the critical z-score would be equal to -2.57
\n" ); document.write( "-8.30 is much greater than that.
\n" ); document.write( "this supports the conclusion that the average lifetime of the bulbs is more than likely less than 36000 hours.
\n" ); document.write( "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.
\n" ); document.write( "let me know if you have any questions.
\n" ); document.write( "theo\r
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