下面是2013年1月13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官方每日一题是collegeboard每天都会发布的题目，关于SAT考试的三个部分的各个题型。下面我们就一起来看一下这个SAT官方每日一题吧。

　　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 train travelingmiles per hour forhour covers the same distance as a train travelingmiles per hour for how many hours?

　　(A) 

　　(B)

 　　(C) 

　　(D) 

　　(E) 

　　The correct answer is B

　　Explanation

　　When the speed of a train in miles per hour is multiplied by the travel time in hours, the distance traveled by the train is obtained. The distance that the first train travels ismiles per hour timeshour, which ismiles. Using the variablefor the travel time, in hours, of the second train, the distance that the second train travels ismiles per hour timeshours, which ismiles. Since the two trains travel the same distance,, which giveshours, the travel time of the second train.

　　下面是一道和SAT官方每日一题相似的题目，供大家练习：

　　On the line above, if , which of the following must be true?

　　Answer Choices

　　(A)

　　(B)

　　(C)

　　(D)

　　(E)

　　The correct answer is B

　　Explanation

　　You can rewrite as , as , as , and as , and then consider the five answer choices.

　　The first answer choice is equivalent to is less than . You know that is less than and that is also less than , but the sum of and might not be less than . Since the question asks which statement must be true, the first answer choice is not the correct answer.

　　The second answer choice is equivalent to is less than . This statement must be true, because is less than and is less than . Although there is no need to consider the other answer choices once you see that the second answer choice must be true, each of the remaining choices could be rewritten in the same way and you could see that they need not be true

　　以上就是关于2013年1月13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。