A mean average of 70 or greater on six exams is needed to get a C in a course. On his first 5 exams, Quincy received grades of 74, 82, 76, 70, and 54.

a) What grade must he receive on his last exam to get a C?

b) A mean average of 80 is needed to get a B in the course. Is it possible for Quincy to get a B? If so, what grade must he receive on the sixth exam?

c) If the lowest grade of the exams already taken is to be dropped, what grade must he receive on his last exam to get a C in the course?

d) If the lowest grade of the exams already taken is to be dropped, would it be possible for Quincy to get a B? If so, what grade would he need to receive on his last exam?