Although beavers can still be found throughout the

[fionaw752]

Hi Ron,
Is choice E wrong because the verb tense "declined" is wrong?
Does "since XXXX year/ century" must ues with "has/have done"? for example, The house on that coner has been empty since 1998.
please correct me, many thanks to you.

Fiona

[RonPurewal]

yes, E can be eliminated on those grounds. well done.

[redexpo]

GMAT prep suggests that "the singular number is not idiomatic." The MGMAT guide 5th edition suggests that "THE numbers of dogs HAVE fallen" is wrong, in favor of "THE number of dogs HAS fallen."

But here we have, "THEIR numbers HAVE declined," which is equivalent to "THE numbers of dogs HAVE fallen," since their is more like a definite article than an indefinite one. It sounds like GMAT prep guidance supersedes MGMAT guidance. The only other option is that these are different idioms. Can someone clear this up? I leveraged this guidance too heavily and ignored a wrong verb tense in E.

[Sage Pearce-Higgins]

Well noticed. However, there are a few considerations here. First, don't trust the official explanations; they're not written by the writers of the questions and they are full of inconsistencies. But, in any case, the explanation refers to the meaning of the sentence, and that's an important thing to consider.

Second, it's great to learn from correct answer choices, clearly 'their numbers have declined' is an okay construction in some contexts (actual GMAT questions are terribly consistent). But I would say that this is a little different from 'the numbers of beavers have declined'; this second phrase doesn't make clear that we're talking about a range of populations (at least, without some further context).

Third, the key to this solving this problem efficiently is the comparison issue, not the idiom issue. I encourage you to read Ron's post above.

[redexpo]

Well noticed. However, there are a few considerations here. First, don't trust the official explanations; they're not written by the writers of the questions and they are full of inconsistencies. But, in any case, the explanation refers to the meaning of the sentence, and that's an important thing to consider.

Thanks. This is news to me. Who writes the explanations in GMAT prep then, and does this apply to quant as well? Does GMAC approve these?

I noticed that the explanations changed considerably in style between the OG and GMAT Prep-related products. The explanations in the former appeared really methodical, though almost incomprehensible, but in GMAT Prep they are more arbitrary though more palatable. For example on the "identify the assumption" questions, in the OG, they negate every assumption, and basically say, that this has no bearing on the argument.

Second, it's great to learn from correct answer choices, clearly 'their numbers have declined' is an okay construction in some contexts (actual GMAT questions are terribly consistent). But I would say that this is a little different from 'the numbers of beavers have declined'; this second phrase doesn't make clear that we're talking about a range of populations (at least, without some further context).

Yeah, I see on reflection that they could mean a series of population numbers over time vs. one population number over time.

Third, the key to this solving this problem efficiently is the comparison issue, not the idiom issue. I encourage you to read Ron's post above.

It is the verb tense error that is relevant between C and E (in my case), but thanks.

[Sage Pearce-Higgins]

Good to hear that my response was useful. In the phrases "THE numbers of dogs HAVE fallen" and "THE number of dogs HAS fallen" the verbs are the same tense. As a choice between different combinations of words, this is an idiom issue and can be found in Appendix A of the SC Strategy Guide.