Question 743034
What is the probability of getting at least 70 shoppers in our sample of 100 
preferring Brand A if the true proportion of the population who prefers Brand A 
is 60%? 
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p = 0.6
std = sqrt[pq/n] = sqrt[0.6*0.4/100] = sqrt(0.24)/10 = 0.049
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z(0.7) = (0.7-0.6)/0.049 = 2.041
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P(x >= 0.7) = P(z > 2.041) = normalcdf(2.041,100) = 0.0206
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Cheers,
Stan H.