Can't understand the answer for this question

[isitu9]

I came across this question in one of the 6 practice tests in MGRE, couldn't find a satisfactory answer in the explanation either :


For this question, the correct answer is 30, that is, number of plants in container

Why can't this be 12, i.e. only number of plants in full shade? The question specifies the minimum number of plants meeting either condition, so shouldn't only plants in full shade be the correct answer?

[tommywallach]

You're thinking about the logic wrong. 30 container plants were sold, and 12 full shade plants were sold. Now, it could be that 12 of the container plants sold were ALSO full shade plants. But that doesn't change the fact that 30 container plants were sold. The minimum number of container/full shade plants sold has to be 30...because we know 30 were sold!

See what I mean?

[ahmar.mehmood]

Same problem with me . . . . Still unable to grasp this answer . . . . I am one day away from my EXAM

[tommywallach]

It's logic, not math.

If 40 people are Spanish, and 20 of those people are cool, and I ask you what is the minimum number of people who are either Spanish or cool (that's the same as the question asked in the posted question, though worded differently), the answer is 40. That's because the overlap doesn't change the fact that at least 40 are Spanish. All of them meet the criterion. Similarly, the 30 container plants ALL meet the criteria. It could be that all 12 shade plants are ALSO container plants, but then you would still have 30 container plants.

-t