Twenty-four percent of primary care doctors think their patients recelve unnecessary medical care. If required, round your answer to four decimal places. (a) Suppose a sample of 300 primary care doctors was taken. Calculate the mean and standad deviation of the sample proportion of doctors who think their patients receive unnecessary medical care. np=? n(1−p)=? E(P^-)=? ​σp= ? (b) Suppose a sampie of 500 primary care doctors was taken. Calculate the mean and standard deviation of the sample proportion of doctors who think their patients recelve unnecessary medical care. np=? n(1−p)=? ​