Although beavers can still be found throughout the

[drathee]

Although beavers can still be found throughout the western United States, their number has declined compared with the eighteenth century, when the abundance of beaver lured armies of European trappers into the Rocky Mountains region to slaughter them for their pelts.

A)their number has declined compared with
B)their numbers have declined compared with
C)their numbers have declined since
D) their numbers have declined in comparison to those of
E)the number of them declined since

This question is from GMAT Prep and the OA is C.
I got the answer right but i am not satisfied with the usage of "their numbers" . To me, "their numbers" sounds as if each of the beavers has a number assigned to them. I think usage of "Their number" would have made more sense in the correct answer.
Please help me in solving this doubt.

[tim]

the best way to resolve your concern about this one is just to accept that apparently the GMAT is okay with this construction. file that away for future reference in case you see something like this on the actual test. the best "explanation" i can give is that there are multiple populations of beavers in the US, and each one has a certain number of individuals in it. perhaps if the GMAT said "their number" it may have suggested there was only one large group of beavers..

[thulsy]

This is a question from Question Pack #1 of the GMATPREP and I have the same query. The official explanation says:
(for Choice A)

"This sentence erroneously compares the number of beavers with the eighteenth century. The singular number is non-idiomatic and does not capture the reality that at different points between the eighteenth century and now, different numbers have described the beaver population in western U.S."

I can understand Tim's explanation that perhaps there are different numbers with respect to different populations of beavers. However, I don't understand the official explanation. I view this as a sequence (as in quantitative):
Let x be the population (i.e. the number), we have a sequence of x:
x1, x2, x3, ...
where x1>x2>x3>...

If we say "the x is declining", x is singular. -That is to say "their number has declined".
If we say "the x1, x2, x3, ... are declining", then that is to say "their numbers have declined".
To me, both singular and plural version are okay - depending on whether we refer to x itself or the terms (xi). Am I wrong?

Thanks in advance.

[tim]

you are safe in your assumption. either version of the term could show up with enough frequency that i would avoid counting either one as wrong. remember, if you can't be 100% sure something is wrong, don't eliminate an answer choice based on that. there is almost always something else in the answer choices that will help you eliminate the four wrong answers..

[thulsy]

I see. Thank you, Tim :)

[tim]

my pleasure!

[ranjeet1975]

Why D is wrong?

in D, "those of eighteenth century" is very well referring to "the number of beavers in eighteenth century".

Am I wrong?

[messi10]

Why D is wrong?

in D, "those of eighteenth century" is very well referring to "the number of beavers in eighteenth century".

Am I wrong?

I think those stands for numbers so the sentence becomes:

their numbers have declined in comparison to numbers of eighteenth century

That doesn't make sense

[RonPurewal]

in choice (d):

* the use of both "declined" and "in comparison to" is redundant. if you have a word that actually makes a comparison (e.g., "declined"), then you don't also use "in comparison to" / "compared to" / etc.

* when you have "that"/"those" in a comparison, it has to be parallel to something that is similarly qualified. for instance:

the cars of today are more fuel-efficient than were those of yesteryear.
--> this works, because "cars of today" and "cars of yesteryear" are both examples of "cars" that are somehow qualified/narrowed down.

but...
cars are more fuel-efficient today than were those of yesteryear.
--> incorrect; you can't compare "those of xxxxx" vs. just "cars".

in choice (d), you just have "their numbers". i.e., "numbers" is qualified by "their", but not by a time period.
therefore, that phrase can make a sensible comparison to the numbers of some other species (Their numbers have declined more quickly than those of most other species)... but not to the numbers of another time period.

[ericyuan0811]

in choice (d):

* the use of both "declined" and "in comparison to" is redundant. if you have a word that actually makes a comparison (e.g., "declined"), then you don't also use "in comparison to" / "compared to" / etc.

* when you have "that"/"those" in a comparison, it has to be parallel to something that is similarly qualified. for instance:

the cars of today are more fuel-efficient than were those of yesteryear.
--> this works, because "cars of today" and "cars of yesteryear" are both examples of "cars" that are somehow qualified/narrowed down.

but...
cars are more fuel-efficient today than were those of yesteryear.
--> incorrect; you can't compare "those of xxxxx" vs. just "cars".

in choice (d), you just have "their numbers". i.e., "numbers" is qualified by "their", but not by a time period.
therefore, that phrase can make a sensible comparison to the numbers of some other species (Their numbers have declined more quickly than those of most other species)... but not to the numbers of another time period.

hello Ron,
from your example above
if we compare one thing in 2 different time periods, we can not omit any time frame;otherwise, it may create ambiguity.

am i right?

1.my bonus of this year is more than that of last year
bonus of this year v.s bonus of last year
2.my bonus is more than that of last year
it may be
(1)as above
(2)my bonus v.s other people's bonus in last year--not the intended meaning

thanks for the help!

[RonPurewal]

hi eric,
remember, you should be careful to avoid spending endless time studying things that haven't actually been tested. have you seen a problem on which this difference was explicitly tested? if so, where?

hello Ron,
from your example above
if we compare one thing in 2 different time periods, we can not omit any time frame;otherwise, it may create ambiguity.

am i right?

not necessarily; for instance, if you have a present-tense construction, you usually won't have to make any explicit mention of the present timeframe.

e.g.
My daughter is taller than she was last year.
--> this says "is", so it's 100% clear that this sentence is referring to her current height. there's no need to write "now" after "taller".

1.my bonus of this year is more than that of last year
bonus of this year v.s bonus of last year

well, there are issues here. specifically, you can't use "that of..." to stand for my bonus. (in other words, "that..." and "those..." don't carry possessive meanings along with them -- that's actually the entire point of these pronouns, to carry the meaning of the noun without the possessive or other descriptor attached to it).

so, for instance, you could have
my dietary requirements are stricter than those of my brothers and cousins
(note "those" = just "dietary requirements")

... but you can't say
my dietary requirements this year are stricter than those of last year.
that's not how "that of"/"those of" works. in this sentence, "those of last year" would just represent "dietary requirements of last year" (WITHOUT "my") -- which would be nonsense.

2.my bonus is more than that of last year
it may be
(1)as above
(2)my bonus v.s other people's bonus in last year--not the intended meaning

* same problem with "that of"; doesn't work here.

* no, this sentence would not be ambiguous, because "is" implies that you are talking about a current bonus. same idea as the sentence above about "my daughter".

[manhhiep2509]

in choice (d):

* the use of both "declined" and "in comparison to" is redundant. if you have a word that actually makes a comparison (e.g., "declined"), then you don't also use "in comparison to" / "compared to" / etc.

Hi Ron.

Please give an example that uses "decline" and express a comparison without using such other comparative phrase as "in comparison to" and "compared to".

I cannot make a sentence that satisfies the above-mentioned requirement.

[RonPurewal]

E.g., Gas prices have declined from their peak value.

[RickyH486]

Although beavers can still be found throughout the western United States, their number has declined compared with the eighteenth century, when the abundance of beaver lured armies of European trappers into the Rocky Mountains region to slaughter them for their pelts.

A)their number has declined compared with
B)their numbers have declined compared with
C)their numbers have declined since
D) their numbers have declined in comparison to those of
E)the number of them declined since

Hi Ron: I learned a great deal of new knowledge from you in this post. Thank you!
When I first attempted this question, I eliminated E because I find "the number of them" sounded weird compare to "their numbers". Could you please shed some light on this part? Thanks

[RonPurewal]

yeah, that's not good writing.

ultimately, though, that's a style issue, so you aren't responsible for it.