The sales of a grocery store had an average of $8,000 per day. The store introdu

Question

The sales of a grocery store had an average of $8,000 per day. The store introduced several advertising campaigns in order to increase sales. To determine whether or not the advertising campaigns have been effective in increasing sales, a sample of 64 days of sales was selected. It was found that the average was $8,500 per day. From past information, it is known that the standard deviation of the population is $1,600. The null hypothesis for this problem is the population average is less than or equal to 8000. The value of the test statistic is

Explanation / Answer

Formulating the null and alternative hypotheses,              
              
Ho:   u   <=   8000  
Ha:    u   >   8000  
              
As we can see, this is a    right   tailed test.      
              
              
Getting the test statistic, as              
              
X = sample mean =    8500          
uo = hypothesized mean =    8000          
n = sample size =    64          
s = standard deviation =    1600          
              
Thus, z = (X - uo) * sqrt(n) / s =    2.5   [ANSWER, TEST STATISTIC]

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