Help! Sample problems

PROBLEM 1 (6pts) Among US Households, only 15% have a landline phone. A telemarketing campaign will involve a SRS of 2300 households. Let X be the number of households that have a landline phone among the 2300 households randomly chosen. ts a) What is the mean of X? ts b) What was the standard deviation of X? Note: the correction factor can be ignored in this case ts c) Assuming X is approximately normal, find P(X>300). PROBLEM 2 (4pts) A supplier of ballpoint pens guarantees a low defective rate. Sara receives a shipment of 400 pens (and unknown to Sara, but known to you, exactly 12 are defective). Sara decides to randomly check 100 pens. Let X be the number of defectives Sara finds among the 100 randomly selected pens. a) The possible values of X are whole numbers ranging from to b) What is the mean of X? is c) What was the standard deviation of X? Hint: you need the correction factor