The sales of a grocery store had an average of 8000 per day

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

Solution

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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