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In 2003, Major League Baseball took steps to speed up the paly of baseball games

ID: 3441561 • Letter: I

Question

In 2003, Major League Baseball took steps to speed up the paly of baseball games in order to maintain fan interest. In a sample of 89 games in 2002, 39 finished in less than 3 hours. A similar survey in 2003 of 83 games found that 44 finished in less than 3 hours. When testing the hypothesis (at the 5% level of significance) a higher percentage of games finished in less than 3 hours in 2003, what is the test statistic? (please round your answer to 2 decimal places)

Here's how I think to answer:

39/89 = .44

44/83= .53

v.44(1-.44)/89 + .53(1-.53)/83 = .0759

(.44-.53) / .0759= 1.19

??????????? Am I on the right track??????

Selected Answer:

2.57

Correct Answer:

1.21 ± 2%

Here's how I think to answer:

39/89 = .44

44/83= .53

v.44(1-.44)/89 + .53(1-.53)/83 = .0759

(.44-.53) / .0759= 1.19

??????????? Am I on the right track??????

Explanation / Answer

Formulating the hypotheses          
Ho: p1^ - p2^   <=   0  
Ha: p1^ - p2^   >   0  
Here, we see that pdo =    0   , the hypothesized population proportion difference.  
          
Getting p1^ and p2^,          
          
p1^ = x1/n1 =    0.530120482      
p2 = x2/n2 =    0.438202247      
          
Also, the standard error of the difference is          
          
sd = sqrt[ p1 (1 - p1) / n1 + p2 (1 - p2) / n2] =    0.075942061      
          
Thus,          
          
z = [p1 - p2 - pdo]/sd =    1.210373192   [ANSWER]  

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