The conclusion of this passage is that the gardener's belief--that jackmanii is the most popular variety of clematis vine among gardeners in North America (NA)--is apparently correct. The word "apparently" is very important here. The conclusion would be substantially different if we were to replace "apparently" with "definitely".
More on that in a moment... but first, why does the author conclude that the belief is
apparently correct?
- The largest clematis nursery in NA sells one million clematis plants per year.
- Of the one million clematis plants sold per year by that nursery, ten percent are jackmanii.
A substantial chunk of the clematis plants sold at the largest nursery are jackmanii. The author reasons that jackmanii's popularity at the largest nursery is a good indicator of its popularity among NA gardeners.
But what about the other 90%? What if another variety of clematis accounts for MORE than 10% of the one million? In that case, jackmanii would not be the most popular variety at the nursery. However, if no other variety accounts for 10% (or more) of the one million, then jackmanii
would be in fact be the most popular variety at the nursery.
Would that
prove that jackmanii is the most popular variety in NA? Not necessarily. But if jackmanii is #1 at the largest nursery, that's certainly EVIDENCE that jackmanii is #1 in NA. Again, we are trying to conclude that the belief is APPARENTLY correct, not that the believe is DEFINITELY correct. As long as we have evidence that jackmanii is the most popular variety among NA gardeners, we're in good shape.
With that in mind, let's look at the answer choices:
Quote:
(A) The nursery sells more than 10 different varieties of clematis
If the nursery sells 10 varieties or fewer, then there would HAVE to be another variety that accounts for more than 10% of the one million plants sold at the nursery. If that were true, then jackmanii could not be the most popular variety at the nursery. Thus, we would
not have evidence that jackmanii is #1 in NA. Without choice (A), the argument falls apart.
Now, does choice (A) PROVE that jackmanii is #1 at the nursery? Not at all... even with 20 varieties, there could be another type that accounts for more than 10% of the million. That, of course, would ruin the argument.
Even if choice (A) is true, the argument may or may not be valid, but that's okay. In other words, choice (A) doesn't PROVE that the author's reasoning is sound. But without choice (A), the author's argument
could not be valid. This is a
required assumption, so keep (A).
Quote:
(B) The largest clematis nursery in North America sells nothing but clematis plants
The nursery could sell many other types of plants. As long as jackmanii is the most popularity variety of
clematis plant sold at the nursery, then the author's reasoning holds up. This is not a required assumption, so eliminate (B).
Quote:
(C) Some of the jackmanii sold by the nursery are sold to gardeners outside North America
If a
substantial portion of jackmanii sales were to gardeners outside of NA, then we might have a problem. That might suggest that jackmanii's popularity at the nursery is NOT a good indicator of jackmanii's popularity among NA gardeners.
Choice (C) only says that SOME of the jackmanii are sold to gardeners outside of NA. In that case, the jackmanii sales at the nursery are probably a good indicator of its popularity among NA gardeners.
Does that make (C) a REQUIRED assumption? If (C) were not true and the nursery ONLY sold jackmanii to gardeners within NA, then that would probably further strengthen the argument. That would give us even more reason to believe that the sales at the nursery are a good indicator of NA popularity. Choice (C) is not a required assumption, so eliminate (C).
Quote:
(D) Most North American gardeners grow clematis in their gardens
It doesn't matter whether clematis is a popular plant in general. The belief is that jackmanii is the most popular variety OF clematis. Even if only a tiny fraction of NA gardeners grow clematis, jackmanii could still be the most popular variety among those gardeners who DO grow clematis. Eliminate (D).
Quote:
(E) For all nurseries in North America that specialize in clematis, at least 10% of the clematis plants they sell are jackmanii.
This is admittedly a little bit tempting: sure, it would strengthen the argument. But this isn't a strengthen question: we need to know whether this is NECESSARY to draw the conclusion.
And it isn't necessary: even if (E) is NOT true -- for example, if jackmanii accounts for less than 10% of clematis plants at a few nurseries -- it's still possible that jackmanii is the most popular. And since (E) isn't necessary, it's not the correct answer.
(A) is the best answer.
Even if A is not true the conclusion can be true. Consider a situation in which there are only two variety of clematis & the largest nursery export the other variety (which consists of 90%) to neighboring country and all of jackmanii's (10%) to NA still jackmanii's will be most popular, hence option A is not necessary for the conclusion to be true.
close
12 Apr 2018, 04:15
Thank you.
