AMC10 2018 A

AMC10 2018 A · Q6

AMC10 2018 A · Q6. It mainly tests Percent, Money / coins.

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, and the score increases by 1 for each like vote and decreases by 1 for each dislike vote. At one point Sangho saw that his video had a score of 90, and that 65% of the votes cast on his video were like votes. How many votes had been cast on Sangho's video at that point?

Sangho 在一个网站上上传了一个视频，观众可以投票表示喜欢或不喜欢该视频。每个视频初始分数为 0，每次喜欢投票分数增加 1，每次不喜欢投票分数减少 1。Sangho 看到他的视频分数为 90，并且当时 65% 的投票是喜欢投票。请问那时总共有多少投票？

(A) 200 200

(B) 300 300

(D) 500 500

(E) 600 600

Answer

Correct choice: (B)

正确答案：（B）

Solution

Let N be the number of votes cast. Then 0.65N of them were like votes, and 0.35N of them were dislike votes. The current score for Sangho’s video is then 0.65N − 0.35N = 0.3N = 90. Thus N = 90 ÷ 0.3 = 300.

设总投票数为 N，则喜欢投票数为 0.65N，不喜欢投票数为 0.35N。当前分数为 0.65N − 0.35N = 0.3N = 90。因此 N = 90 ÷ 0.3 = 300。

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