2018 AMC 10A 第 6 题

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所有题目均经美国数学协会(MAA)官方合法授权使用。

6.

Sangho 把一个视频上传到某网站,观看者可以投喜欢票或不喜欢票。每个视频的初始分数为 00,每收到一张喜欢票,分数增加 11;每收到一张不喜欢票,分数减少 11

某一时刻,Sangho 看到视频的分数为 9090,而且所有投票中有 65%65\% 是喜欢票。当时这个视频一共收到了多少票?

Sangho uploaded a video to a website where viewers can vote that they like or dislike a video. Each video begins with a score of 0,0, and the score increases by 11 for each like vote and decreases by 11 for each dislike vote.

At one point Sangho saw that his video had a score of 90,90, and that 65%65\% of the votes cast on his video were like votes. How many votes had been cast on Sangho's video at that point?

200200

300300

400400

500500

600600

答案:B
知识点:百分数一次方程
难度评级:900
解答:

喜欢票占 65%65\%,所以不喜欢票占 35%35\%。因此视频分数等于总票数的 65%35%=30%65\% - 35\% = 30\%

已知分数为 9090,所以总票数为 90÷30%=30090 \div 30\% = 300

因此正确答案是 B

If 65%65\% of votes were like votes, then 35%35\% of votes are dislike votes. Then Sangho's score is 65%35%=30%65\% - 35\% = 30\% the total number of votes.

We know that Sangho's score is 90,90, so the total number of votes is 90÷30%=300.90 \div 30\% = 300.

Thus, B is the correct answer.

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