Read the following SAT test question and thenclick on a button to select your answer.
The sum of the positive odd integers less than 50 issubtracted from the sum of the positive evenintegers less than or equal to 50. What is theresulting difference?
(A) 0
(B) 25
(C) 50
(D) 100
(E) 200
答案：B
解析：
The sum of the positive odd integers less than 50 is1 + 3 + 5 + ... + 45 + 47 + 49, and the sum of thepositive even integers less than or equal to 50 is 2 + 4 + 6 + ... + 46 + 48 + 50. When the first sum issubtracted 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 correctanswer is 25.
相关推荐：
