SAT官方每日一题：2012年4月27日

　　下面是是2012年4月27日的SAT官方每日一题的内容，是关于数学方面的，题型是选择。

　　SAT官方每日一题之数学---选择：

　　Mathematics > Standard Multiple Choice

　　Read the following SAT test question and then click on a button to select your answer.

　　A jar contains only red marbles and green marbles. If a marble is selected at random from the jar, the probability that a red marble will be selected is . If there are 36 green marbles in the jar, how many red marbles are there in the jar?

　　Answer Choices

　　(A) 18

　　(B) 24

　　(C) 54

　　(D) 72

　　(E) 108

　　The correct answer is D

　　Explanation

　　Choice (D) is correct. Let r be the number of red marbles in the jar. The probability of selecting a red marble is equal to the number of red marbles divided by the total number of marbles. Since the probability of selecting a red marble is , it follows that . There are 36 green marbles and r red marbles, so the previous equation becomes . This simplifies to2(r + 36) = 3r, or 2r + 72 = 3r. Therefore, the number of red marbles, r, is 72.

　　下面是一道和SAT官方每日一题相似的题目，供大家练习：

　　If is an odd integer, which of the following is an even integer?

　　Answer Choices

　　(A)

　　(B)

　　(C)

　　(D)

　　(E)

　　The correct answer is E

　　Explanation

　　If is an odd integer, then and are odd integers. Similarly, choices C and D are odd integers. Since an odd integer subtracted from another odd integer is always an even integer, is even.

　　以上就是关于2012年4月27日SAT官方每日一题中数学部分的详细内容，包括了题目和选项以及答案，后面附有一道相关的练习题。大家可以在备考SAT的过程中关注SAT每日一题的内容，这样就可以更好有不间断的练习，也就能在日积月累的过程中得到提高。