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PROBLEM 1 Among US Households, only 20% have a landline phone. A telemarketing campaign will involve a SRS of 2000 households.

PROBLEM 1 


Among US Households, only 20% have a landline phone.  A telemarketing campaign will involve a SRS of 2000 households.  Let Xbe the numberof households that have a landline phone among the 2000 households randomly chosen. 




What is the mean of X?



What was the standard deviation of X?


Note: the correction factor can be ignored in this case



AssumingXis approximately normal, find P(X>300).






PROBLEM 2 


A supplier of ballpoint pens guarantees a low defective rate. Sara receives a shipment of 500 pens (and unknown to Sara, but known to you, exactly 13 are defective).  Sara decides to randomly check 100 pens.  Let Xbe the numberof defectives Sara finds among the 100 randomly selected pens.




 The possible values of Xare whole numbers ranging from _____ to _____.




 What is the mean of X?




What was the standard deviation of X?


Hint: you need the correction factor

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