Statistics Instructors assume that course grades in the population of undergraduate students taking their courses follow the normal distribution with parameters ( = 72, = 8). Use the table of cumulative probabilities to answer questions below. 1. Find proportion of students with grades below 68 2. Evaluate the chance that a randomly selected student has grade above 74 3. What proportion of students will have grades between 70 and 80 4. Find the chance that a randomly selected students will be graded above 66