GRE offiicial Guide Spoiler P 783 / 818 Spoiler

Please give me some advice on how can I detect questions such as this.
I frequently make the mistake of choosing the median percentage, in this problem it is 18% instead of choosing the median week.
How to remedy this.

My Exam is coming up, need some advice on avoiding this type of mistakes in the Charts


There’s no specific advice for this, other than just reading the question again and confirm you’re actually answering the right question