In: Math
Elwin Osbourne, CIO at GFS, Inc., suspects that at least 25% of e-mail messages sent by GFS employees are not business related. A random sample of 300 e-mail messages was selected to test this hypothesis at the 0.01 level of significance. Fifty-four of the messages were not business related. The appropriate decision is _______.
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 increase the sample size  | 
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 gather more data  | 
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 reject the null hypothesis  | 
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 fail to reject the null hypothesis  | 
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 maintain status quo  | 
Null hypothesis
   
   
          
       
Alternative hypothesis      
           
          
       
We have for given example,      
           
Population proportion value is =0.25      
       
x=54   
          
       
n=300          
   
Level of significance =   0.01  
           
Estimate for sample proportion =54/300=0.18
          
       
Z test statistic formula for proportion  
           
   
=-2.8  
P value =0.0024.................by using Z table or Excel =NORMSDIST(-2.8)
P value < 0.01
| reject the null hypothesis |