The amount of sleep that elementary school children get per night follows a normal distribution with a mean of 9.5 and a standard deviation of .55 hours. a) find the proportion of elementary school children who get between 9 and 10 hours of sleep per night. sketch the normal curve and shad the area under the curve that is the answer to the question.

b) is it unusual for an elementary school student to get at least 12 hours of sleep? justify your answer.