Coin tosses in a large class of introductory statistics students, the professor has each student toss a coin 16 times and calculate the proportion of his or her tosses that were heads. the students then report their results, and the professor plots a histogram of these several proportions. a. what shape would you expect this histogram to be? why? b. where do you expect the histogram to be centered? c. how much variability would you expect among these proportions? d. explain why a normal model should not be used here.