The distribution of the scores on a certain exam is N(70, 10), which means that the exam scores are Normally distributed with a mean of 70 and standard deviation of 10.
a. Sketch the curve and label, on the x-axis, the position of the mean, the mean plus or minus one standard deviation the mean plus or minus two standard deviations, and the mean plus or minus three standard deviations.
b. Find the probability that a randomly selected score will be between 50 and 90. Shade the region under the Normal curve whose area corresponds to this probability.