4) A student has had an average of 6 and $1 / 2$ in the first four assignments. What grade must they get on the fifth to achieve an average of 7?
(B) 8 and $1 / 2$
(C) 9
(D) 10
(E) they can't do it.
4) The answer is (C)

In the first four assignments, the student scored $4 \cdot(6+1 / 2)=26$ points in total. To have an average of 7, they must total 35 points. Therefore, in the fifth assignment, they must score 9.