dj-- that's what I get at first blush too, but I think it's wrong.
Just to make the math easier, say that 28 (rather than 27) percent of the population don't buy either paper.
That means that 72 percent buy X, Y, or both.
If they are in a 7:1 ratio, it could be that 63% buy X, and 9% buy y.
or, it could mean that 62% buy x exclusively, and 2% buy y exclusively, and that 8% buy both..
(2) solves this problem. I think we need them both.
We are looking for the percent of the population that purchase newspaper Y, and not
the percent of the population that purchase exclusively newspaper Y.
Therefore, the two situations you proposed against A will draw the same result. Here's an example:
Supose there are 100 people.
Case 1: 62 purchase X exclusively and 9 purchase Y exclusively
Then the answer would be obviously 9%
Case 2: 62 buy X exclusively, 2 buy Y exclusively and 7 buys them both
Total number of people buying paper Y = 7+2 = 9
The answer is still 9%
Do I make any sense?
This is a Kaplan
question btw and the answer provided is C, although I still believe is A.