单选题
Directions: In the following questions, choose the best answer from the five choices listed.
单选题
If it is now June, what month will it be 400 months from now?
A. January B. April C. June
D. October E. December
A. January B. April C. June
D. October E. December
【正确答案】
D
【答案解析】Since 400= 12×33+4, 100 months is 4 months more than 33 years. So 33 years from now it will again be June, and 4 months later it will be October. [See Section 14-P] **Look for a pattern. Since there are 12 months in a year, after every 12 months it will again be June; i.e., it will be June after 12, 24, 36, 48 120 360 months. So, 396 (33 × 12) months from now, it will again be June. Count 4 more months to October.
单选题
If 
of the members of the school chorus are boys, what is the ratio of girls to boys in the chorus?
of the members of the school chorus are boys, what is the ratio of girls to boys in the chorus?
【正确答案】
B
【答案解析】Use TACTIC 3 in Chapter 11: pick an easy-number. Since 
of the members to-use are boys, assume there are 9 members, 5 of whom are boys. Then the other 4 are girls, and the ratio of girls to boys is 4 to 5, or 
of the members to-use are boys, assume there are 9 members, 5 of whom are boys. Then the other 4 are girls, and the ratio of girls to boys is 4 to 5, or
单选题
What is the volume of a cube whose total surface area is 54?
A. 9B. 27C. 54D. 81E. 729
A. 9B. 27C. 54D. 81E. 729
【正确答案】
B
【答案解析】Since the surface area is 54, each of the six faces of the cube is a square whose area is 54 + 6 = 9. Then each edge is 3, and the volume is 33 = 27.