SAT官方每日一题 2017年3月26日.

SAT官方每日一题 2011年3月25日 SAT题型:Mathematics > Standard Multiple Choice Please enter an answer. Read the following SAT test question and 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? Answer Choices (A) 0 (B) 25 (C) 50 (D) 100 (E) 200 答案:B 解析: Explanation 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 minus 1) plus (4 minus 3) + ... + (48 minus 47) + (50 minus 49), which is just 1 + 1 + 1 + ... + 1, where there are 25 ones. Therore, the correct answer is 25.