Question 560128:  If 2% of all calculators are defective, find the mean, variance, and standard deviation of a lot of 400 calculators. 
 Answer by stanbon(75887)      (Show Source): 
You can  put this solution on YOUR website! If 2% of all calculators are defective, find the mean, variance, and standard deviation of a lot of 400 
 
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mean = np = 400*0.02 = 8 
variance = npq = 8*0.98 = 7.84 
std = sqrt(npq) = sqrt(7.84) = 2.8 
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Cheers, 
Stan H. 
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