{{U}}Directions:{{/U}} In the following questions, choose the best answer from the five choices listed.

单选题 Camille's average on her 6 math tests this marking period is 75. Fortunately for Camille, her teacher drops each student's lowest grade, and this raises her average to 85. What was her lowest grade?

A、 (A) 20
B、 (B) 25
C、 (C) 30
D、 (D) 40
E、 (E) 50

【正确答案】 B

【答案解析】On six tests combined, Camille earned a total of 6 × 75 = 450 points [TACTIC El]. The total of her five best grades is 5 × 85 = 425 points, so her lowest grade was 450 -425 = 25. **Assume that Camille's five best grades were each 85. Then each one has a deviation of 10 points above the average of 75, and the total deviation above 75 is 5 × 10 = 50 points. Therefore, her one bad grade must have been 50 points below 75.

单选题 What is the surface area in square inches of a cube whose volume is 216 cubic inches?

A、 (A) 36
B、 (B) 54
C、 (C) 216
D、 (D) 324
E、 (E) 1296

【正确答案】 C

【答案解析】
Since the volume of the cube is 216 cubic inches, we have e³ = 216

单选题 Last year Leo bought two paintings. This year he sold them for $2000 each. On one, he made a 25% profit, and on the other he had a 25% loss. What was his net loss or profit?

A、 (A) He broke even.
B、 (B) He lost less than $100.
C、 (C) He lost more than $100.
D、 (D) He earned less than $100.
E、 (E) He earned more than $100.

【正确答案】 C

【答案解析】On the first painting, Leo made a 25% profit, so if he bought it for x, he sold it for x + .25x = 1.25x = 2000

x = 2000 + 1.25 = 1600. His profit was $400. On the second painting, Leo lost 25%, so if he bought it for y, he sold it for y -.25y = .75y = 2000