scores on a 100-point final exam administered to all applied calculus classes at a large university are normally distributed with a mean of 69.5 and a standard deviation of 28.55. (a) what percentage of students taking the test had scores between 60 and 80? (round your answer to one decimal place.) % (b) what percentage of students taking the test had scores of at least 90? (round your answer to one decimal place.) % (c) what percentage of students taking the test had scores that were more than one standard deviation away from the mean? (round your answer to one decimal place.) % (d) at what score was the rate of change of the probability density function for the scores a maximum?