Suppose a firm that produces light bulbs wants to know whether it can say that i

Question

Suppose a firm that produces light bulbs wants to know whether it can say that its light bulbs typically last more than 1500 hours. Hoping to find support for their claim, the firm collects a random sample of n = 25 light bulbs and records the lifetime (in hours) of each bulb. The information related to the hypothesis test is presented below.

Sample mean 1509.5

Sample standard deviation 24.27

What is the test value that you would use to conduct this test? Place your answer, rounded to 3 decimal places in the blank. For example, 1.234 would be a legitimate entry.

Explanation / Answer

Formulating the null and alternative hypotheses,              
              
Ho:   u   <=   1500  
Ha:    u   >   1500  
              
As we can see, this is a    right   tailed test.      
              
Getting the test statistic, as              
              
X = sample mean =    1509.5          
uo = hypothesized mean =    1500          
n = sample size =    25          
s = standard deviation =    24.27          
              
Thus, t = (X - uo) * sqrt(n) / s =    1.957148743 = 1.957 [ANSWER]          
              

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