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in a random sample of 200 adults what is the probability th Exit polling is a po

ID: 3150234 • Letter: I

Question

in a random sample of 200 adults what is the probability th Exit polling is a popular technique used to determine the outcome of an election prior to results being tafted Suppose a referenda to increase funding for education the ballot In a large town (voting population over 100.000) An exit poll of 300 voted lor the referendum How Maty are the results of your sample if the population proportion of voters in the town m favor of the referendum is 0 49? Based on your result. comment on tho dangers of using exit polling to call elections How likely are the results of your sample If the population proportion of voters in the town m favor of the referendum is O.49 The probabity that more than 153 people voted for the referendum is

Explanation / Answer

a)

We first get the z score for the critical value:          
          
x = critical value =    153.5      
u = mean = np =    147      
          
s = standard deviation = sqrt(np(1-p)) =    8.658521814      
          
Thus, the corresponding z score is          
          
z = (x-u)/s =    0.750705506      
          
Thus, the left tailed area is          
          
P(z <   0.750705506   ) =    0.226414954 [ANSWER]

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IF YOU DO NOT USE CONTINUITY CORRECTION, THIS IS THE ALTERNATIVE:

We first get the z score for the critical value:          
          
x = critical value =    153      
u = mean = np =    147      
          
s = standard deviation = sqrt(np(1-p)) =    8.658521814      
          
Thus, the corresponding z score is          
          
z = (x-u)/s =    0.692958929      
          
Thus, the left tailed area is          
          
P(z <   0.692958929   ) =    0.244167663 [ANSWER]

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As we can see, P > 0.05, so it is not unusual.

OPTION A. [ANSWER, A]