GMAC Test Paper 30

[Samy]

Researchers have announced that the magnetic fields emitted by one manufacturer’s
security surveillance system, of which type there are 200,000 worldwide, can interfere
with pacemakers and that this interaction can bring on missed or irregular heartbeats,
nausea, breathlessness, dizziness, and even fainting.

A. of which type there are 200,000 worldwide, can interfere with pacemakers and
that
B. of which, worldwide, there are 200,000 of that type, and which can interfere with
pacemakers, and
C. of which type there are 200,000 worldwide, they can interfere with pacemakers
and
D. 200,000 of which type exist worldwide, interfering with pacemakers, and
E. 200,000 of that type existing worldwide and can interfere with pacemakers, and

Given Ans is D. Can you explain How?

[dbernst]

Samy,

The correct answer is A. Choice A correctly utilizes parallel construction (Researchers have announced that...and that...); moreover, the "core" of answer choice A is grammatical (Researchers have announced that fields emited can interfere...and that this interaction can bring..)

Answer choice D, the supposedly correct response, contains several questionable elements. First, "200,000" of which type seems to actually question which type these security systems are. Second, magnetic fields "interfering" with pacemakers is an incorrect verb tense. Finally, choice D changes the intended meaning by implying that the machines rather than the magnetic fields are causing the problem.

Hope that helps!
-dan

Researchers have announced that the magnetic fields emitted by one manufacturer’s
security surveillance system, of which type there are 200,000 worldwide, can interfere
with pacemakers and that this interaction can bring on missed or irregular heartbeats,
nausea, breathlessness, dizziness, and even fainting.

A. of which type there are 200,000 worldwide, can interfere with pacemakers and
that
B. of which, worldwide, there are 200,000 of that type, and which can interfere with
pacemakers, and
C. of which type there are 200,000 worldwide, they can interfere with pacemakers
and
D. 200,000 of which type exist worldwide, interfering with pacemakers, and
E. 200,000 of that type existing worldwide and can interfere with pacemakers, and

Given Ans is D. Can you explain How?

[Samy]

Thanks a lot for all your replies.
This time they came in earlier than expected (Ellipses ) :cool:
I have a lot more doubts so hope you or someone from your excellent company can clear them.

Thanks :D

[gbyhats]

Hi Dear Manhattan Instructors : )

Sorry about digging this 8-year-old post.

My question is why is the expression "200,000 of which" seems to be question which type of security system?

as shown in the bold part:

Answer choice D, the supposedly correct response, contains several questionable elements. First, "200,000" of which type seems to actually question which type these security systems are. Second, magnetic fields "interfering" with pacemakers is an incorrect verb tense. Finally, choice D changes the intended meaning by implying that the machines rather than the magnetic fields are causing the problem.

--

To me, this type of expression seems ok:

e.g. I have lots of video games, twelve of which are bought from Amazon

"twelve of which" means: among these games, 12 are from Amazon

--

Do I misunderstand this type of expression?

[tim]

My question is why is the expression "200,000 of which" seems to be question which type of security system?

I do not understand this question at all, because it has too many grammatical errors. Your example seems to demonstrate your understanding of the concept though. If you have any further questions, please post them so we can help you.

[gbyhats]

Hi Dear Tim,

Thank you very much for your timely reply! :)

Let me take another shot at rephrasing my question:

Can I ask to explain little bit more: what's wrong with "200,000 of which type" in choice D?

a complete version of choice D is below:

Researchers have announced that the magnetic fields emitted by one manufacturer’s security surveillance system, 200,000 of which type exist worldwide, interfering with pacemakers, and this interaction can bring on missed or irregular heartbeats, nausea, breathlessness, dizziness, and even fainting.

[tim]

Plug the antecedent in for "which" and take a look at the clause (you should be able to identify that "which" is replacing "security surveillance system"):

"200,000 of security surveillance system type exist worldwide"

This doesn't work, but if you had said

"200,000 types of security surveillance system exist worldwide"

it would have been okay. So "type" cannot exist in the singular *or* in its current location in this answer choice.

[gbyhats]

Hi Tim,

Oh man, what you've said is so obvious

Why I didn't realize that!

Thank you very very much Tim!!!

[RonPurewal]

this thread is now locked, because the old paper tests are a prohibited source. (please read the forum rules.)

[RonPurewal]

also——really——don't use the paper tests as a source of SC problems.
GMAT SC has evolved significantly since the days of the paper tests. the paper-test SC problems test LOTS of things that have since been eliminated, especially "native-speaker advantage" items such as idioms, word order, and so on.

seriously... studying these things is, in essence, studying for an entirely different test (that doesn't even exist anymore). don't do it.