In a large section of a statistics class , the points for the final exam are normally distributed , with a mean of 76 and a standard deviation of 8. Grades are assignedrsuch that the top 10 % receive A's , the next 20 % received B's , the middle 40 % receive C's , the next 20 % receive D's , and the bottom 10 % receive F's . Find the lowest score on the final exam that would qualify a student for an A , a B , a C , and a D.