Statistics: Averages and Arithmetic Means

1. The average (arithmetic mean) of four numbers is 80. If three of the numbers are 60, 90, 70, what is the fourth number?

(A) 70
(B) 80
(C) 90
(D) 100
(E) 110

2. The average (arithmetic mean) of 7, 22, and $x$ is 25. What is the value of $x$?

(A) 7
(B) 46
(C) 22
(D) 44
(E) 75

3. Gean took four math tests so far in the first semester. His average score was 68. If a C is given to students who have an average score of 70 to 80, what is the minimum score he needs to receive on his next test to get a C in the class?

(A) 82
(B) 95
(C) 66
(D) 74
(E) 78

4. Vanessa took seven math tests in the second semester. Her average score was 88. Her last test is a final exam worth two tests. If an A is given to students who have an average score of 90 and above, what is the minimum score she needs to receive on her final to get an A in the class?