GRE Practice Question Incorrect?

Question

This is a sample GRE question. The answer claims that we cannot make an inference due to insufficient information. > *Compare the following quantities:* > > Of the 25 people in Fran’s apartment building, there are 9 residents > who use the roof only for tanning and 8 residents who use the roof > only for gardening. The roof is only used by tanners and gardeners. > > **Quantity A:** The ratio of people who use the roof to total residents > > **Quantity B:** 17:25 > > In this question, we do not know if there is any overlap between > tanners and gardeners. How many, if any, residents do both activities? > Since we don’t know, the relationship cannot be determined from the > information given. Given that this question specifies **only**, how can the answer imply that there may be an overlap? E.g. If I use the roof for tanning *and* gardening then I do **not** use the the roof *only* for tanning. Thoughts?

Answer 1

My thoughts are:

1. 9 residents use the roof only for tanning
2. 8 residents who use the roof only for gardening
3. And x number of residents use roof for both gardening and tanning

The problem never says that people cannot be doing both. It does say "The roof is only used by tanners and gardeners" which is not the same thing as "The roof is by tanners only and gardeners only".

There is no information about these "x" people so we cannot make an inference due to insufficient information.

Hope this helps.

Answer 2

The tanners and the gardeners account for 17 people. The use of the roof by the other 8 residents is not given.