SAT备考数学练习题（2）

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sat考试官方网站每日一题小结，以下是SAT数学部分。

Read the following SAT test question, then click on a button to select your

answer.

The sum of the positive odd integers less than 50 is subtracted from the sum

of the positive even integers less than or equal to 50. What is the resulting

difference?

A.0

B.25

C.50

D.100

E.200

Correct Answer: B

Here"s Why:

The sum of the positive odd integers less than 50 is 1 + 3 + 5 + ··· + 45 +

47 + 49, and the sum of the positive even integers less than or equal to 50 is 2

+ 4 + 6 + ··· + 46 + 48 + 50. When the first sum is subtracted from the second,

the terms can be regrouped to form (2 – 1) + (4 – 3) + ··· + (48 – 47) + (50 –

49), which is just 1 + 1 + 1 + ··· + 1, where there are 25 ones. Therefore, the

correct answer is 25.

Difficulty: Hard

Question Type: Standard Multiple Choice