It is currently 02 Apr 2020, 01:40

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# QOTD # 1-2 Supernovas in the Milky Way are the likeliest sou

Author Message
TAGS:
Founder
Joined: 18 Apr 2015
Posts: 10110
Followers: 209

Kudos [?]: 2503 [1] , given: 9501

QOTD # 1-2 Supernovas in the Milky Way are the likeliest sou [#permalink]  21 Sep 2016, 02:11
1
KUDOS
Expert's post
00:00

Question Stats:

51% (02:44) correct 48% (04:50) wrong based on 31 sessions
Supernovas in the Milky Way are the likeliest source for most of the cosmic rays reaching Earth. However, calculations show that supernovas cannot produce ultrahigh-energy cosmic rays (UHECRs), which have energies exceeding 1018 electron volts. It would seem sensible to seek the source of these in the universe’s most conspicuous energy factories: quasars and gamma-ray bursts billions of light-years away from Earth. But UHECRs tend to collide with photons of the cosmic microwave background—pervasive radiation that is a relic of the early universe. The odds favor a collision every 20 million light-years, each collision costing 20 percent of the cosmic ray’s energy. Consequently, no cosmic ray traveling much beyond 100 million light-years can retain the energy observed in UHECRs.
For the following question, consider each of the choices separately and select all that apply.

It can be inferred that the author of the passage would agree with which of the following about the origin of UHECRs that reach Earth?

• The origin is something other than supernovas in the Milky Way.
• The origin is most likely something other than very distant quasars or gamma-ray bursts.
• The origin is most likely no more than a little over 100 million light-years away from Earth
.

[Reveal] Spoiler: OA
A,B, and C

In the context of the author’s argument, the last sentence performs which of the following functions?

A) It explains a criterion that was employed earlier in the argument.
B) It shows that an apparently plausible position is actually self-contradictory.
C) It is a conclusion drawn in the course of refuting a potential explanation.
D) It overturns an assumption on which an opposing position depends.
E) It states the main conclusion that the author is seeking to establish

[Reveal] Spoiler: OA
C

Practice Questions
Question: 1 and 2
Page: 45

_________________

Need Practice? 20 Free GRE Quant Tests available for free with 20 Kudos
GRE Prep Club Members of the Month: Each member of the month will get three months free access of GRE Prep Club tests.

Founder
Joined: 18 Apr 2015
Posts: 10110
Followers: 209

Kudos [?]: 2503 [0], given: 9501

Re: QOTD # 1-2 Supernovas in the Milky Way are the likeliest sou [#permalink]  21 Sep 2016, 02:12
Expert's post
Explanation

1) All three choices are correct. The question asks about claims the author would agree with. Choice A is correct: The passage states that supernovas in the Milky Way “cannot produce ultrahigh-energy cosmic rays.” Choice B is correct: Since very distant quasars and gamma-ray bursts are
“billions of light-years away from Earth,” they are too far away for a UHECR to reach Earth. Choice C is correct: The last sentence of the passage states that “no cosmic ray traveling much beyond 100 million light-years can retain the energy observed in UHECRs.”

2) The last sentence is the conclusion of an argument in the last half of the passage; it puts a constraint on the possible origin of UHECRs relative to Earth and thereby rules out the possibility, mentioned earlier in the passage, that distant quasars and gamma-ray bursts could be the origin of UHECRs. Therefore Choice C is correct. It is important to note that the last sentence does not show any plausible position to be self-contradictory (Choice B), and that it does not state the author’s main conclusion (Choice E), since it is relevant to only one of the two hypotheses considered in the passage.
_________________

Need Practice? 20 Free GRE Quant Tests available for free with 20 Kudos
GRE Prep Club Members of the Month: Each member of the month will get three months free access of GRE Prep Club tests.

Manager
Joined: 26 Jun 2017
Posts: 104
Followers: 1

Kudos [?]: 46 [1] , given: 38

Re: QOTD # 1-2 Supernovas in the Milky Way are the likeliest sou [#permalink]  24 Jul 2017, 03:34
1
KUDOS
Carcass wrote:
Explanation

1) All three choices are correct. The question asks about claims the author would agree with. Choice A is correct: The passage states that supernovas in the Milky Way “cannot produce ultrahigh-energy cosmic rays.” Choice B is correct: Since very distant quasars and gamma-ray bursts are
“billions of light-years away from Earth,” they are too far away for a UHECR to reach Earth. Choice C is correct: The last sentence of the passage states that “no cosmic ray traveling much beyond 100 million light-years can retain the energy observed in UHECRs.”

2) The last sentence is the conclusion of an argument in the last half of the passage; it puts a constraint on the possible origin of UHECRs relative to Earth and thereby rules out the possibility, mentioned earlier in the passage, that distant quasars and gamma-ray bursts could be the origin of UHECRs. Therefore Choice C is correct. It is important to note that the last sentence does not show any plausible position to be self-contradictory (Choice B), and that it does not state the author’s main conclusion (Choice E), since it is relevant to only one of the two hypotheses considered in the passage.

The first question's third choice seems ambiguous as the passage points out much beyond than 100 million light years, however, the answer choice (C) says no more than 100 million light years. How that can be?
_________________

What you think, you become.

Founder
Joined: 18 Apr 2015
Posts: 10110
Followers: 209

Kudos [?]: 2503 [0], given: 9501

Re: QOTD # 1-2 Supernovas in the Milky Way are the likeliest sou [#permalink]  25 Jul 2017, 01:33
Expert's post
Yes, I totally agree with you if not for a small word you forget to mention in that phrase.

Quote:
The origin is most likely no more than a little over 100 million light-years away from Earth

with this in the passage

Consequently, no cosmic ray traveling much beyond 100 million light-years can retain the energy observed in UHECRs.

They perfectly match.

Hope this helps

Regards
_________________

Need Practice? 20 Free GRE Quant Tests available for free with 20 Kudos
GRE Prep Club Members of the Month: Each member of the month will get three months free access of GRE Prep Club tests.

Manager
Joined: 26 Jun 2017
Posts: 104
Followers: 1

Kudos [?]: 46 [1] , given: 38

Re: QOTD # 1-2 Supernovas in the Milky Way are the likeliest sou [#permalink]  25 Jul 2017, 11:55
1
KUDOS
Carcass wrote:
Yes, I totally agree with you if not for a small word you forget to mention in that phrase.

Quote:
The origin is most likely no more than a little over 100 million light-years away from Earth

with this in the passage

Consequently, no cosmic ray traveling much beyond 100 million light-years can retain the energy observed in UHECRs.

They perfectly match.

Hope this helps

Regards

Thank you, the test organizers are so cunning. Also, what you think my level is if I make such a mistake? Thanks in advance.
_________________

What you think, you become.

Founder
Joined: 18 Apr 2015
Posts: 10110
Followers: 209

Kudos [?]: 2503 [0], given: 9501

Re: QOTD # 1-2 Supernovas in the Milky Way are the likeliest sou [#permalink]  26 Jul 2017, 02:30
Expert's post
Difficult to judge based on one question only. It could be a silly mistake or something related with your English skills.
_________________

Need Practice? 20 Free GRE Quant Tests available for free with 20 Kudos
GRE Prep Club Members of the Month: Each member of the month will get three months free access of GRE Prep Club tests.

Intern
Joined: 02 Oct 2019
Posts: 1
Followers: 0

Kudos [?]: 1 [1] , given: 0

Re: QOTD # 1-2 Supernovas in the Milky Way are the likeliest sou [#permalink]  14 Oct 2019, 09:51
1
KUDOS
Can anyone help me to understand the 2nd question, please? it seems that the answer choice B is correct. I have been thinking why C is correct and it seems ok to be the right answer but I just can't understand why B is not the correct one. Because to me, it feels like quasar and gamma rays were plausible position for the cosmic ray's source and the last line was contradictory to this explanation for the source of those cosmic rays. I just can't find my mistake.
Founder
Joined: 18 Apr 2015
Posts: 10110
Followers: 209

Kudos [?]: 2503 [2] , given: 9501

Re: QOTD # 1-2 Supernovas in the Milky Way are the likeliest sou [#permalink]  15 Oct 2019, 02:29
2
KUDOS
Expert's post
BipashaAmin wrote:
Can anyone help me to understand the 2nd question, please? it seems that the answer choice B is correct. I have been thinking why C is correct and it seems ok to be the right answer but I just can't understand why B is not the correct one. Because to me, it feels like quasar and gamma rays were plausible position for the cosmic ray's source and the last line was contradictory to this explanation for the source of those cosmic rays. I just can't find my mistake.

Venomous passage

Analyzing it as the following:

X (Supernovas) are composed by $$x_1,x_2,$$ ......so forth x-rays type

Supernovas in the Milky Way are the likeliest source for most of the cosmic rays reaching Earth.

However, calculations show that supernovas cannot produce ultrahigh-energy cosmic rays (UHECRs), which have energies exceeding 1018 electron volts. It would seem sensible to seek the source of these in the universe’s most conspicuous energy factories: quasars and gamma-ray bursts billions of light-years away from Earth.

However, our X does not produce a CERTAIN type of rays which can not reach our planet BECAUSE 20% of those rays are lost every 20 millions of years. In 100 million light-years they become zero, basically.

Therefore our conclusion is the following

Consequently, no cosmic ray traveling much beyond 100 million light-years can retain the energy observed in UHECRs.

In the context of the author’s argument, the last sentence performs which of the following functions?

A) It explains a criterion that was employed earlier in the argument.

No. It is a conclusion not an explanation. it is the result

B) It shows that an apparently plausible position is actually self-contradictory.

It does not contradict anything before

C) It is a conclusion drawn in the course of refuting a potential explanation.

Yes. It is. Our potential explanation is that some other source is the origin of our rays. And the last sentence concludes that the rays from supernovas can not reach or pass over 100. The explanation is the match calculation above

D) It overturns an assumption on which an opposing position depends.

Nothing here is assumed

E) It states the main conclusion that the author is seeking to establish

The author does not establish anything. We have specific facts. Basically E says that we have an assumption but we do not. D and E says the same thing
_________________

Need Practice? 20 Free GRE Quant Tests available for free with 20 Kudos
GRE Prep Club Members of the Month: Each member of the month will get three months free access of GRE Prep Club tests.

Re: QOTD # 1-2 Supernovas in the Milky Way are the likeliest sou   [#permalink] 15 Oct 2019, 02:29
Display posts from previous: Sort by