这部分主要考察学生的计算准确度：涉及到小学难度的移项、通分、约分;初中难度的消元、换元、数列、解二次方程;高中难度的排列组合、二次函数、幂指数运算等。如果排除粗心的因素，学生普遍更容易在高中难度的题型上犯错误，所以建议考生在考前一定把相关的概念和公式记清楚，并且多练习这类题目。

The table above shows the number of registered voters in 2012, in thousands, in four geographic regions and five age groups. Based on the table, if a registered voter who was 18 to 44 years old in 2012 is chosen at random, which of the following is closest to the probability that the registered voter was from the Midwest region?

A . 0.10

B . 0.25

C . 0.40

D . 0.75

本题解析：According to the table, in 2012 there was a total of 14,766 + 47,896 = 62,662 registered voters between 18 and 44 years old, and 3,453 + 11,237 = 14,690 of them were from the Midwest region. Therefore, the probability that a randomly chosen registered voter who was between 18 and 44 years old in 2012 was from Midwest region is 1469062662≈0.2341469062662≈0.234. Of the given choices, 0.25 is closest to this value.

Choices A, C, and D are incorrect and may be the result of errors in selecting the correct proportion or in calculating the correct value.

正确答案：B

The table above represents the 50 movies that had the greatest ticket sales in 2012, categorized by movie type and Motion Picture Association of America (MPAA) rating. What proportion of the movies are comedies with a PG-13 rating?

A . 225225

B . 950950

C . 211211

D . 1125

本题解析： According to the table, of the 50 movies with the greatest ticket sales in 2012, 4 are comedy movies with a PG-13 rating. Therefore, the proportion of the 50 movies with the greatest ticket sales in 2012 that are comedy movies with a PG-13 rating is 450450 , or equivalently, 225225 .

Choice В is incorrect; 950950 is the proportion of the 50 movies with the greatest ticket sales in 2012 that are comedy movies, regardless of rating. Choice С is incorrect; 211=422211=422 is the proportion of movies with a PG-13 rating that are comedy movies. Choice D is incorrect; 1125=22501125=2250 is the proportion of the 50 movies with the greatest ticket sales in 2012 that have a rating of PG-13.

正确答案： A