The ultimate pendulum clock, indeed the ultimate mechanical clock of a

Hello...

Let me try to help you with the first question.

1. The passage most strongly suggests that its author would agree with which of the following statements about clocks?

A) Before 1921 no one had designed a clock that used electricity to aid in its timekeeping functions.

B) Atomic clocks depend on the operation of mechanisms that were invented by William Shortt and first used in the Shortt clock.

C) No type of clock that keeps time more stably and accurately than a Shortt clock relies fundamentally on the operation of a pendulum.

D) Subtle changes in the earth's rotation slightly reduce the accuracy of all clocks used in observatories after 1921.

E) At least some mechanical clocks that do not have pendulums are almost identical to Shortt clocks in their mode of operation.

Let us talk about Options C and D.

C - This option would have been extreme if the phrase "than a Shortt Clock" was not present. If that was the case, then it would have talked about all the clocks. However, the phrase "than a Shortt Clock" links it to the passage.

D - The addition of the word "mechanical" to Option D would not make any difference. It still talks about all mechanical clocks - The passage doesn't give information on this.

Hope that resolves the doubt.

All the best,

Thanks,

Saikiran Dudyala
Byju's GMAT Verbal Expert.

It is the other way around.

vacuum chamber => firmly sealed.

The passage tells us that the primary pendulum was housed in a vacuum chamber. It certainly implies that the chamber was firmly sealed (else you cannot maintain vacuum).
So option (B) must be true.

Hi Will2020

For a detail question in RC, you need to be able to put your finger (pretty much literally) on one or more sentences in the passage that PROVE your answer. As you know, extreme language in answer choices makes them suspicious - it raises the bar of how strong the proof must be to support the answer. Your correct inference answer choice must NEVER be based on speculation ("well, it COULD be true, maybe sorta"). If you are speculating, you are not approaching the question effectively.

So on to the answer choices you mentioned:
A - Yes, "no one" is extreme. But what kills this answer choice is what it's about - using electricity to aid in timekeeping functions, and when was the first time that a clock did that. Do we have any idea about the history of this? Absolutely not. The passage isn't talking about this; the focus is more on the accuracy of these Shortt clocks as best-in-class for mechanical clocks.
D - Indeed, "all clocks" is the killer here. Atomic clocks are held up in this passage as seemingly the most accurate clocks, and we have no information about whether changes in the earth's rotation affect them.
E - How could this possibly make sense? The Shortt clock relies on this special setup with the two pendulums that the passage spends a bunch of time telling us about. So how could other clocks with no pendulums be "almost identical" in their mode of operation? It's pretty counter-intuitive, so the author would have needed to dedicate some time to explaining this. Of course, the author did not touch this topic at all (modes of operation that don't use pendulums but are still similar) so this answer is out of scope.

My advice to you is to get much deeper into the passage when you read and tackle the questions. It's like a courtroom trial and you need to be clear about the evidence that is presented to you: what it says, and what it doesn't say. If you just kind of skim through the passage casually, you are not preparing yourself to be effective on these 700-level questions.

Does this help? Let me know.

Best, Jenn

"The earth's rotation" isn't derived from any other phrase in the text. That exact phrase occurs BOTH in the text AND in the answer!

The text says that Shortt clocks enabled researchers to detect
seasonal variations in the earth's rotation

The answer choice:
the earth's rotation varies from one time of year to another

The color-coded pieces go together. "Varies" and "variation" are forms of the same word, so you only have to recognize that seasons are times of year.

It took me 10.26 minutes to solve this one....
I know its an unacceptably long. But I think seeing the length and cogent thinking required in this passage (specially in Q1 andQ3),
this passage deserves that much time.

I am sceptical about the solution of Q1, Yes the clock works on pendulum, but in the first line of the passage it is mentioned it is the best of the mechanical clocks, in the C option is too generalised saying No other clock......

Also in Q4 I was hinged between A and C, ending up choosing A. The reason being that since we in the end of 3rd para and starting of the 4th para it is mentioned about how Shott's clock is able to predict about tides. We can predict that only when we know about how the tides are caused....


Can anybody tell me where I am wrong????????????

Could someone shine light on question number 2? How can it be D. IMO C is directly implied in the passage.

The only statement that I could find related to option D was the following,


and that implies it is the rotation that helped discover something about the clock and not the other way around.

Thanks in advance!

Hi jennpt,


Question 3. The passage most strongly suggests that the study
described in the third paragraph would not have been possible in the absence of

A) accurate information regarding the times at which
high and low ocean tides occurred at various locations during 1984

B) comparative data regarding the use of Shortt clocks in observatories between 1921 and 1932

C) a non-Shortt clock that was known to keep time extremely precisely and reliably

D) an Innovative electric-power source that was not available in the 1920s and 1930s

E) optical data-transmission devices to communicate between the U.S. Naval Observatory and other
research facilities

Can you please explain why A is wrong? in the exam, I was stuck between A and C. I did not pick C because I though it was too obvious. I could not find enough grounds to eliminate A. In parg 3, it says he clock was
responding to the slight tidal distortion of the earth due
to the gravitational pull of the moon and the sun.
how would they have found this out without accurate times at which
high and low ocean tides occurred? or is it because it says "various locations" when the passage did not mention anything about those locations?

Hi jennpt, can you help with the first question?

I got this in my GMAT prep test today. I was trying to find 4 incorrect options. I eliminated C because it looked too extreme. When I got to E, I realized that I had eliminated 4 options, so the answer must be E.
Any tips on how I can avoid such mistakes?

Waiting to resolve the the same query as below.

Hello,

please see below for explanation:

This is an According to the passage question, so there shouldnt be much analysis here.

The only piece of information you need here is this The first indications of seasonal variations in the earth's rotation were gleaned by the use of Shortt clocks.


Question 2. According to the passage, the use of Shortt clocks
led to the discovery that

A) optical sensing equipment can be used effectively in
time-keeping systems Trap to get you lost in the details

B) atomic clocks can be used in place of pendulum
clocks in observatoriesTrap to get you lost in the details

C) tides occur in solid ground as well as in oceans This is indeed stated like you pointed out. However, the trap here is that it has nothing to do with what Shortt Clocks helped in discovering. Shortt Clocks did not help to discover that tides occur in solid ground and in the oceans. It helped discover indications of seasonal variations in the earth's rotation. The passage then continues to explain how tides in ocean and solid are related to that (which we don't really need to know and its only meant to confuse us.

D) the earth's rotation varies from one time of year to another. This is what I talked about above. It's a rephrase of The first indications of seasonal variations in the earth's rotation were gleaned by the use of Shortt clocks..[/color]

E) pendulums can be synchronized with one another electronically It's clear that this has nothing to do with anything

Hello GMATNinja

Can you please help in solving Q1 and Q4.

Thanks!

There's been some great discussion of both of these questions in this thread.

Is there something specific that previous explanations by jennpt Alok322, saurabh3, arvind910619, and Dabu3790 have not addressed? If so, please let us know.

Hi GMATNinja, for Q1, would D have been correct if instead of:

Subtle changes in the earth's rotation slightly reduce the accuracy of all clocks used in observatories after 1921.

It would have been:

Subtle changes in the earth's rotation slightly reduce the accuracy of all mechanical clocks used in observatories after 1921.

Question 4 is still not clear. Can someone please help with a detailed explanation on this.

VeritasKarishma egmat generis

GMATNinja, can you explain the reasoning behind option C in
question 1

Hi BrightOutlookJenn GMATNinja VeritasKarishma! How can we eliminate the wrong answer choices? I did notice the strong language in A - "no one" - and D - "all clocks" - are they wrong because of it? What about E? Many tks!

Hi BrightOutlookJenn GMATNinja VeritasKarishma! Question 2 was tough because it lacked a key word to search for. So, I ended up spending a lot of time in this question. What was your thought process to solve the question? I had to go trough each AC, using process of elimination to finally pick the right answer, but doing so was very time consuming and I couldn't prove the right AC during the test. Tks!