Since the 1940's the farms and ranches of the Great Plains have been s

Question

Project SC Butler: Day 183: Sentence Correction (SC1) 
 For SC butler Questions  Click Here

Since the 1940's the farms and ranches of the Great Plains have been supplied with water from the Ogallala aquifer; this underground reservoir contained an estimated quadrillion gallons of water, which equal Lake Huron, but now reserves are becoming depleted.

A) which equal Lake Huron

B) which equal Lake Huron's

C) equal to Lake Huron¡'s

D) the equivalent of Lake Huron's

E) the equivalent of Lake Huron

A) which equal Lake Huron

B) which equal Lake Huron's

C) equal to Lake Huron¡'s

D) the equivalent of Lake Huron's

E) the equivalent of Lake Huron

generis · Accepted Answer

OFFICIAL EXPLANATION

Project SC Butler: Day 183: Sentence Correction (SC1)

•  equal  and  equivalent  do not mean the same thing.
• track very carefully on what is being compared in each option
• think about the logical meaning of the words

• very generally, use  equal  to talk about quantitative things, but use  equivalent  to talk about qualitative things
The word  equivalent  typically means that two things are similar in function or quality.
Quality can include size or capacity.
This rule is not set in stone. It's a guideline.

We use  equal  to talk about numeric relationships.
• a number, numerical quantity, or quantifiable measurement is  equal  (not "equivalent") to another number, numerical quantity, or measurement
-- one quadrillion equals 1,000 trillion

• this sentence is  not  trying to compare the number of gallons of water used up from a reservoir to the number of gallons of water contained in Lake Huron. 
-- no option offers a quantity word such as "the number of" or "as many as are" in Lake Huron.
-- there is no quantity to compare  a quadrillion gallons  to. Don't use  equal . Use equivalent.

• both the absence of a phrase such as "number of"   and the word "equivalent" indicate that 
1) we are talking about enormous volume (capacity)
2) we are being given a real-world example in order to imagine that enormous capacity.

That is, the sentence means that a quadrillion gallons of water is the equivalent of the capacity of Lake Huron.
The farmers and ranchers essentially drained the equivalent of Lake Huron.

Here is a similar sentence from the  New York Times  in which area in square feet is "the equivalent of": 
 . . . a local copper mill, . . . a facility encompassing more than one million square feet — roughly the equivalent of 17 football fields.  ( July, 2018,   here

A quadrillion is unthinkably huge. Lake Huron is conceivably huge—not perfectly conceivable, but a lot better than "a quadrillion gallons." 
 
  THE PROMPT

THE OPTIONS

•  gallons of water   equal  a  lake . Gallons of water are identical to a lake? 
 No . 
A quadrillion gallons is a number. Lake Huron is a body of water.  Wrong.  
• the situation is just as faulty if we say that "1 quadrillion gallons  of water, " which equal Lake Huron.  Wrong.  A quadrillion is a number.
• We might be able to correct this option  if  we said
. . . an estimated quadrillion gallons of water, which are about equal to the number that are in Lake Huron
(We can imply "gallons of water.")
That not-available sentence is clunky, but it is logical. 
Eliminate A

•   incorrect identity.   
-- "which" means "gallons of water." (More on this issue below.)
-- The verb following  which  is  equal , plural. The word "gallons" is plural. "Water" is not.
•  One quadrillion gallons of water  from a reservoir is a number that is not identical to, or the same as, Lake Huron's  .
• a reference to a quantity is missing
-- The bracketed words   are permissible ellipsis (omission of words). 
-- But we need a reference to quantity of gallons of water in Lake Huron. None exists. 
Eliminate B
(alternatively, if you feel uncertain, KEEP B and compare to another answer)

• This option is the same as Option (B), but the words "which are" have been removed 
• The sentence still says that a quadrillion gallons of water from an underground reservoir are identical to Lake Huron's  .
The quadrillion gallons of water in the aquifer that the farmers and ranchers used up is not identical to   water in Lake Huron. 
• we still need a reference of some kind to a quantity: . . . an estimated quadrillion gallons, a number equal to the number in Lake Huron . . . 
Eliminate C

• Now we have a doubly bad situation.
• equivalent  to Lake  Huron's   ?
No. Gallons of water are measurable. A measurable quantity takes equal. 
The possessive word "Huron's" implies "gallons of water," and ruins this answer. We should say that one quantity is equal to or the same as another  quantity  
-- "equivalent" in this context is used to indicate similar qualities. 
-- A quadrillion gallons of water from the reservoir and Lake Huron's gallons of water are not equivalent in quality. 
Eliminate (D)

• bingo. The capacity of the almost-empty reservoir is about a quadrillion gallons of water,   the equivalent of   Lake Huron
• the point of the sentence comes through. Farmers and ranchers have drained the equivalent of Lake Huron.

Suppose that you held back B or C. 
Neither B nor C contains a comparison between a number (a quadrillion) and another number (of gallons of water in Lake Huron).
Neither B nor C says ". . . a quadrillion gallons of water, about as many as are contained in Lake Huron. . . ."
In this split, stay with the guideline. 
-- Compare a number or quantity to another number or quantity, and use "equal." 
-- Compare degrees of similarity -- similar uncountable capacities or volumes -- by using  equivalent .

Options B and C make incorrect identities.

The answer is E

Quick recap of WHICH. The word "which" does NOT have to refer to the immediately preceding noun.   
Which can "reach back" over a prepositional phrase to reach the MAIN NOUN in a prepositional phrase.
This usage is very common on the GMAT.
--   which  is a nonessential modifier.  
British English speakers, you will have to be a little careful because B.E. does not treat "which" as nonessential.
Remember: comma + which = nonessential
-- the prepositional phrase "of water" is essential (gallons of what? Oil? Vodka? NO. Gallons of water)
-- we have two modifiers that refer to the same noun. Only one can go right next to the noun.
-- so the essential modifier trumps the nonessential modifier, but both can still refer to their noun.
-- the nonessential modifier WHICH can still refer to its noun: it is allowed to reach back over an essential modifier to get to its noun.

This topic thread,  here ,  contains a lot of useful information, as well as a post by me about the use of which, which can be found  here .. 
That post discusses how "which" is an exception to the noun modifier "Touch Rule" and list a couple of official questions as examples.
I also discuss how to figure out the noun that is being modified by the which-clause. (Check the verb that follows  which .)

COMMENTS

cyclops12321  and  sathik63  , welcome to SC Butler.

This question requires you to think really hard about logic or to have read every day.
Google the names of prominent U.S. newspapers and (in quotation marks) "the equivalent of."
You will get pages' of hits.

This question riffs on an official question that made aspirants a little frustrated. 
That question emphasized numbers. This one emphasizes capacity. 
The official question is  here .

A quadrillion gallons of water is an enormous volume of water: one thousand trillion gallons. 
The question emphasizes this enormous volume (of water used up by farmers and ranchers) and the enormous capacity of the Ogallala aquifer by invoking a famous lake—also of enormous volume.

Anyone who posted was brave. Smiley faces to all, and kudos for the correct answer.

suchithra · Answer

This is a question that tests the difference between equal and equivalent and the comparisons. The underlined portion is comparing the gallons of water in the aquifier with the gallons of water in the lake.

First split Equal vs Equivalent
Equal can be used for numbers. 
Equivalent suggests that two things are similar in quality/function or in other characteristics and when one one can be replaced with the other.

In this question, we are comparing the gallons. Therefore Equal is correct. Eliminate D&E.

Of the remaining options, you can eliminate A because we are not comparing gallons with the lake. 
Between B&C, We have to find an answer that avoid ambiguity in comparison i.e compare either gallons or water. 
According to B, the comparison is

quadrillion gallons of water, which equal lake horon's (gallons of water)

Here the verb "equal" is plural which means the comparison has to be lake Horon's gallons of water and not lake Horon's water

According to C,
 quadrillion gallons of water, equal to lake horon's (Water or gallon's of water)

Here its not clear if we are comparing to the water or to the gallons.

Therefore B is correct IMO.

sampriya · Answer

A)  which  equal Lake Huron

B)  which  equal Lake Huron's

in options A and B which can refer to water and gallons of water. "which" is wrong usage

D) the equivalent of Lake Huron's
D has a meaning error

E) the equivalent of Lake Huron

water is illogically compared to the lake

C) equal to Lake Huron¡'s

option C is the correct option

chaitralirr · Answer

Since the 1940's the farms and ranches of the Great Plains have been supplied with water from the Ogallala aquifer; this underground reservoir contained an estimated quadrillion gallons of water, which equal Lake Huron, but now reserves are becoming depleted.

A) which equal Lake Huron

B) which equal Lake Huron's

C) equal to Lake Huron¡'s

D) the equivalent of Lake Huron's

E) the equivalent of Lake Huron

A) which equal Lake Huron  the comparison incorrectly compares. The use of possessive is needed here and the use of relative clause which is incorrect

B) which equal Lake Huron's  though possessive is used "which should be replaced"

C) equal to Lake Huron¡'s  uses correct comparison

D) the equivalent of Lake Huron's  the change of word from equivalent to equal is incorrect

E) the equivalent of Lake Huron  same error as D

If we look at the underlined portion we need to compare the water in both lake

TheNightKing · Answer

These 2 options are straight up Incorrect. We are comparing illogical things. We are basically saying "reservoir is equal to the Lake". We should be comparing reservoir to another lake's reservoir.

which refers to the "quadrillion gallons of water" and that is not the intended meaning.

So honestly both look Okay to me. But I will pick C over D and 2 reasons for doing that are: 1. C is more concise. 2. the equivalent of changes the meaning. I am not sure what could be the huge difference between the two but C is a better fit.

IMO C.

sathik63 · Answer

Split 1: usage of which

Which is referring to water in both A and B. It can be eliminated straight away

Split 2: equal vs equivalent

we are comparing the quantity of water. Hence equal is correct. 
D and E can be eliminated. Only C remains.

Also A and E can be eliminated for incorrect comparison.

C is the clear winner.

Posted from my mobile device

Shishou · Answer

Since the 1940's the farms and ranches of the Great Plains have been supplied with water from the Ogallala aquifer; this underground reservoir contained an estimated quadrillion gallons of water, which equal Lake Huron, but now reserves are becoming depleted.

A) which equal Lake Huron   the possessive is needed here the volumes must be equated not the volume and the lake itself

B) which equal Lake Huron's  one could say which refers to water but should 
refer to the gallons of water but I am doubtful since the way the sentence is written I do not know if the phrase "...of water" can be placed anywhere else. besides the verb equal is plural and hence which refers to the millions of gallons of water. I will eliminate this for concision issues

C) equal to Lake Huron¡'s  this is a much better construction. it compares the volume of the reservoir to Lake Huron's

D) the equivalent of Lake Huron's  I am not too sure what is wrong with this .it could be the use of equivalent rather than equal. I will eliminate this for concision issues as well

E) the equivalent of Lake Huron  makes the same mistake as A : it compares the volume of the reservoir to the lake itself when it should be comparing their respective 
volumes

answer is C. I will wait for the OA since there are some few issues I need clarification on

eakabuah · Answer

Option A: Since the 1940's the farms and ranches of the Great Plains have been supplied with water from the Ogallala aquifer; this underground reservoir contained an estimated quadrillion gallons of water, which  equal   Lake Huron , but now reserves are becoming depleted.
I think the  which clause  rightly modifies the noun phrase  an estimated quadrillion gallons of water . A noun modifier or which clause is able to reach beyond a prepositional modifier as long as the prepositional modifier(s) modifies the intended noun to be modified.   of water   modifies  quadrillion gallons of water . There are two errors in option A. It is erroneous to say that an estimated quadrillion gallons of water equal lake Huron. The possessive form, Lake Huron, or the phrase that of Lake Huron addresses this issue. Sir  generis  I have an issue with the which clauses. I am confused about the structure. Do they not require an auxiliary verb  are ? The second issue relates to the idiom equal to, with the preposition to missing. Eliminate option A.

Option B: Since the 1940's the farms and ranches of the Great Plains have been supplied with water from the Ogallala aquifer; this underground reservoir contained an estimated quadrillion gallons of water, which  equal   Lake Huron's , but now reserves are becoming depleted. 
The only issue is the omission of   to   from the idiom equal to, which required because we are comparing two things. Eliminate option B.

Option C: Since the 1940's the farms and ranches of the Great Plains have been supplied with water from the Ogallala aquifer; this underground reservoir contained an estimated quadrillion gallons of water,  equal to   Lake Huron's , but now reserves are becoming depleted.
Correct. The estimated volume of water in the aquifer (quadrillion gallons of water) is equal to Lake Huron's (the estimated volume of water in Lake Huron).

Option D: Since the 1940's the farms and ranches of the Great Plains have been supplied with water from the Ogallala aquifer; this underground reservoir contained an estimated quadrillion gallons of water,   the  equivalent of   Lake Huron's , but now reserves are becoming depleted.
An adjective, equivalent to, rather than a noun, the equivalent, is needed to appropriately compare the estimated gallons in the aquifer and that in Lake Huron's. Had Option D been  equivalent to Lake Huron's , I am not sure it would still be incorrect. Eliminate option D.

Option E: Since the 1940's the farms and ranches of the Great Plains have been supplied with water from the Ogallala aquifer; this underground reservoir contained an estimated quadrillion gallons of water,   the  equivalent  of  Lake Huron , but now reserves are becoming depleted.
Just as in option D, the noun the equivalent is not appropriate. In addition, Lake Huron has to be in the possessive form  Lake Huron's  in order to make the comparison logical.

cyclops12321 · Answer

Equal means number and Equivalent means in quantity or capacity(not necessary a number). Here we are comparing the capacity of the Aquifer with that of Lake Huron. This eliminates answers A,B,C.Between D & E, E seems to be a better options as the possesive "Huron's" seems un-necessary and weird.
Also, when you use equivalent of, which takes the form Noun + Preposition, it is generally affixed with "the" as in : One Apple is the nutritional equivalent of two bananas.

Sunil

TheNightKing · Answer

Wow! Nobody (who selected the answer E) has posted an explanation! Looking out for this one.

generis · Answer

The official explanation is  HERE

mykrasovski · Answer

generis  although I got the question right, I could not really explain why I picked (E). I read GMATNinja's explanation in the link that you provided, but still not 100% sure whether the usage of "equivalent to" in the  NYTimes article  is correct. Here is the sentence for your convenience:

According to a recent report by the Carnegie Foundation for the Advancement of Teaching, ''Corporate Classrooms: The Learning Business,'' American companies are providing job training and general education for nearly eight million people, about equivalent to the enrollment in the nation's four-year colleges and universities.

Is the sentence trying to say that 8 million people from companies are equivalent to (in their quality and function) those in colleges?

Thank you in advance.

cyclops12321 · Answer

According to a recent report by the Carnegie Foundation for the Advancement of Teaching, ''Corporate Classrooms: The Learning Business,'' American companies are providing job training and general education for nearly eight million people, about equivalent to the enrollment in the nation's four-year colleges and universities.

Is the sentence trying to say that 8 million people from companies are equivalent to (in their quality and function) those in colleges?

Thank you in advance.

My 2cents : 
 I am pretty sure you cannot use equivalent or equal here. People( Irrespective of the number) can't be equal/equivalent to other people ( if you understand the meaning). . The correct use might be " as many as". I am sure experts will pitch in with their opinion.

Sunil

AdityaHongunti · Answer

generis   jennpt 
 indeed we are comparing the "capacity" and not the actual numerical volume.
Nevertheless, how is Lake Huran itself sufficient to stand for its capacity?

i mean in option D : equivalent to Lake Huran's (capacity)

doesnt this make the option D righht??

here how are we not emphasizing the need for a referrant of Huran's capacity?? how can we just say X gallons of water (capacity) is equivalent to Lake HUran?? capacity should be compared to capacity !

Please explain . Thankyou

Shishou · Answer

generis  so what you are saying is that B and C make a mistake like this :
I have 5 books, equal to Michael's when it should be I have 5 books, equal to the number Michael has. if we had said " I have 5 books,equivalent to Michael's " then would this construction be correct?

AkashM · Answer

GMATNinja ,  generis ,

As Aditya mentioned above, isn't ' equivalent to Lake Huron's (capacity ) a better comparison than just ' Lake Huron '?

Could you please help.

Thanks in advance!

CEdward · Answer

So the first thing that I have observed is that in complex questions, the comparison being made can be between two things that are not explicitly mentioned (capacity in this case).

As a follow-up, is it a general rule that in instances where we have a noun acting as a container (reservoir/Lake Huron), that the comparison is always made between the container rather than the content?

I too wonder about the questions above.

VerbalBot · Answer

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GMAT Sentence Correction (SC - EA only) Questions

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