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Recently some scientists have concluded that meteorites foun
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08 Oct 2019, 04:41
08 Oct 2019, 04:41
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Recently some scientists have concluded that meteorites found on Earth and long believed to have a Martian origin might actually have been blasted free of Mars's gravity by the impact on Mars of other meteorites. This conclusion has led to another question: whether meteorite impacts on Earth have similarly driven rocks from this planet to Mars. According to astronomer S.A. Phinney, kicking a rock hard enough to free it from Earth's gravity would require a meteorite capable of making a crater more than 60 miles across. Moreover, even if Earth rocks were freed by meteorite impact, Mars's orbit is much larger than Earth's, so Phinney estimates that the probability of these rocks hitting Mars is about one-tenth as great as that of Mars's rocks hitting Earth. To demonstrate this estimate, Phinney used a computer to calculate where 1,000 hypothetical particles would go if ejected from Earth in random directions. He found that 17 of the 1,000 particles would hit Mars.
Question 1
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Question Stats:
48% (01:44) correct
52% (01:52) wrong based on 65 sessions
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(A) presenting an argument to support a particular hypothesis
(B) suggesting an answer to a theoretical question
(C) questioning the assumptions of a research project
(D) criticizing experimental results
(E) explaining the origin of certain scientific data
Show: :: OA
B
Question 2
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69% (00:51) correct
31% (01:15) wrong based on 61 sessions
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18. According to the passage, which of the following events may have initiated the process that led to the presence on Earth of meteorites from Mars?
(A) A meteorite struck the Earth with tremendous velocity.
(B) A meteorite collided with Mars.
(C) Approximately 1,000 rocks were ejected from Mars.
(D) The orbits of Earth and Mars brought the planets to their closest points.
(E) Rocks from a meteorite impact broke free of Earth's gravity.
Show: :: OA
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Question 3
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80% (00:59) correct
20% (01:27) wrong based on 54 sessions
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19. The passage suggests that which of the following is true concerning the probability that a rock, if ejected from Mars, will hit the Earth?
(A) The probability is increased when particles are ejected from Mars in random directions.
(B) The probability is increased by the presence of large craters on the surface of Mars.
(C) The probability is decreased when Mars's orbit brings the planet close to Earth.
(D) The probability is greater than the probability that rock from Earth will hit Mars.
(E) The probability is less than the probability that a rock from Earth will escape Earth's gravity.
Show: :: OA
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Question 4
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70% (01:21) correct
30% (01:19) wrong based on 56 sessions
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20. Which of the following, if true, would cast most doubt on Phinney's estimate of the probability of Earth rocks hitting Mars?
(A) Rather than going in random directions, about 25 percent of all particles ejected from Earth go in the same direction into space.
(B) Approximately 100 meteorites large enough to make a noticeable crater hit the Earth each year.
(C) No rocks of Earth origin have been detected on Mars.
(D) The velocity of ' rocks escaping from Earth's gravity is lower than the velocity of meteorites hitting the Earth.
(E) No craters more than 60 miles across have been found on Mars
Show: :: OA
A
Re: Recently some scientists have concluded that meteorites foun
[#permalink]
13 Nov 2019, 18:00
13 Nov 2019, 18:00
4
Below is how I analyzed it:
Which of the following, if true, would cast most doubt on Phinney's estimate of the probability of Earth rocks hitting Mars?
Now, what do we know about Phinney's probability estimate calculation of Earth's rocks hitting Mars (which is 1/10 th probability of Mars' rocks hitting Earth - also answer to Q19):
=> It was calculated on a computer
=> We know that 1000 hypothetical particles if ejected from Earth in random directions, only 17 would hit Mars
To doubt the calculation, something like the below should happen:
i. the computer which Phinney was less computation intensive, and when tested on a supercomputer (sort of, with higher computation resources) probability estimate changed
ii. with the increase in number of hypothetical particles, the number of hypothetical particles hitting Mars actually decreases (or increases)
Now lets at the options:
(A) Rather than going in random directions, about 25 percent of all particles ejected from Earth go in the same direction into space.
Mars is orbiting, now if some % of particles are fired in a specific direction - for majority of the time it would miss Mars and thus distort the probability. However there would be an instantaneous rise in % when this direction points to Mars
Overall, probability estimate calculation would not be valid with this mechanism. Hence (A)
(B) Approximately 100 meteorites large enough to make a noticeable crater hit the Earth each year.
=> Based on the passage, size of a meteorite is not a decisive parameter for the probability estimate calculation, hence out-of-scope
(C) No rocks of Earth origin have been detected on Mars.
=> Again out-of-scope, it doesnt impact or cast a doubt on the estimate calculation (probably, the equipment used were not capable enough to detect it etc.). We need to find an option which challenges the estimate calculation. Also note, passage is detailing a hypothetical empiricism, an answer to (again) a theroetical question. Nothing in the passage, relates to actual
(D) The velocity of ' rocks escaping from Earth's gravity is lower than the velocity of meteorites hitting the Earth.
=> Velocity is not the decisive parameter, even if the velocity is high enough, since Mars' obrit is larger than of Earth, chance is probability estimate wont be distorted.
(E) No craters more than 60 miles across have been found on Mars
=> Again out of scope, similar explanation to (C)
Which of the following, if true, would cast most doubt on Phinney's estimate of the probability of Earth rocks hitting Mars?
Now, what do we know about Phinney's probability estimate calculation of Earth's rocks hitting Mars (which is 1/10 th probability of Mars' rocks hitting Earth - also answer to Q19):
=> It was calculated on a computer
=> We know that 1000 hypothetical particles if ejected from Earth in random directions, only 17 would hit Mars
To doubt the calculation, something like the below should happen:
i. the computer which Phinney was less computation intensive, and when tested on a supercomputer (sort of, with higher computation resources) probability estimate changed
ii. with the increase in number of hypothetical particles, the number of hypothetical particles hitting Mars actually decreases (or increases)
Now lets at the options:
(A) Rather than going in random directions, about 25 percent of all particles ejected from Earth go in the same direction into space.
Mars is orbiting, now if some % of particles are fired in a specific direction - for majority of the time it would miss Mars and thus distort the probability. However there would be an instantaneous rise in % when this direction points to Mars
Overall, probability estimate calculation would not be valid with this mechanism. Hence (A)
(B) Approximately 100 meteorites large enough to make a noticeable crater hit the Earth each year.
=> Based on the passage, size of a meteorite is not a decisive parameter for the probability estimate calculation, hence out-of-scope
(C) No rocks of Earth origin have been detected on Mars.
=> Again out-of-scope, it doesnt impact or cast a doubt on the estimate calculation (probably, the equipment used were not capable enough to detect it etc.). We need to find an option which challenges the estimate calculation. Also note, passage is detailing a hypothetical empiricism, an answer to (again) a theroetical question. Nothing in the passage, relates to actual
(D) The velocity of ' rocks escaping from Earth's gravity is lower than the velocity of meteorites hitting the Earth.
=> Velocity is not the decisive parameter, even if the velocity is high enough, since Mars' obrit is larger than of Earth, chance is probability estimate wont be distorted.
(E) No craters more than 60 miles across have been found on Mars
=> Again out of scope, similar explanation to (C)
Re: Recently some scientists have concluded that meteorites foun
[#permalink]
30 May 2020, 16:59
30 May 2020, 16:59
1
17. The passage is primarily concerned with
(B) suggesting an answer to a theoretical question
correct- This conclusion has led to another question: whether meteorite impacts on Earth have similarly driven
rocks from this planet to Mars.
18. According to the passage, which of the following events may have initiated the process that led to the presence on Earth of meteorites from Mars?
(B) A meteorite collided with Mars.
correct- by the impact on Mars of other meteorites
19. The passage suggests that which of the following is true concerning the probability that a rock, if ejected from Mars, will hit the Earth?
(D) The probability is greater than the probability that rock from Earth will hit Mars.
correct- the probability of these rocks hitting Mars is about one-tenth as great
as that of Mars's rocks hitting Earth
20. Which of the following, if true, would cast most doubt on Phinney's estimate of the probability of Earth rocks hitting Mars?
POE
(A) Rather than going in random directions, about 25 percent of all particles ejected from Earth go in the same direction into space.
Correct- So Phinney estimates that the probability.....To demonstrate this estimate, Phinney used a computer
This would increase the probability
(B) suggesting an answer to a theoretical question
correct- This conclusion has led to another question: whether meteorite impacts on Earth have similarly driven
rocks from this planet to Mars.
18. According to the passage, which of the following events may have initiated the process that led to the presence on Earth of meteorites from Mars?
(B) A meteorite collided with Mars.
correct- by the impact on Mars of other meteorites
19. The passage suggests that which of the following is true concerning the probability that a rock, if ejected from Mars, will hit the Earth?
(D) The probability is greater than the probability that rock from Earth will hit Mars.
correct- the probability of these rocks hitting Mars is about one-tenth as great
as that of Mars's rocks hitting Earth
20. Which of the following, if true, would cast most doubt on Phinney's estimate of the probability of Earth rocks hitting Mars?
POE
(A) Rather than going in random directions, about 25 percent of all particles ejected from Earth go in the same direction into space.
Correct- So Phinney estimates that the probability.....To demonstrate this estimate, Phinney used a computer
This would increase the probability
