Recently some scientists have concluded that meteorites found on Earth

Question

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 Line 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.   1 
 1. The passage is primarily concerned with

(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

2 
 2. 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.

3 
 3. 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.

4 
 4. 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

Skywalker18 · Answer

All correct in 4 mins 10 seconds, including 1 min 40 seconds to read

1. The passage is primarily concerned with 
(B) suggesting an answer to a theoretical question - Correct, the theoretical question is "whether meteorite impacts on Earth have similarly driven rocks from this planet to Mars"

2. 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. 
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 Line Mars's gravity by the impact on Mars of other meteorites

3. 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
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.

4. 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. - Correct,
So the overall probability can increase or decrease depending on whether this direction itself.
(B) Approximately 100 meteorites large enough to make a noticeable crater hit the Earth each year. - incorrect, the actual number of not relevant, he is just using 1000 as an example and show the proportion of hits.
(C) No rocks of Earth origin have been detected on Mars. - incorrect, whether rocks of Earth origin have been detected on Mars is irrlevant
(D) The velocity of ' rocks escaping from Earth's gravity is lower than the velocity of meteorites hitting the Earth. - incorrect
(E) No craters more than 60 miles across have been found on Mars- Irrelevant, the size of craters in Mars is not relevant

thinkvision · Answer

Any easy one, took close to 3.5 minutes!

1. The passage is primarily concerned with

(A) presenting an argument to support a particular hypothesis
(B) suggesting an answer to a theoretical question - Correct, stated in the passage
(C) questioning the assumptions of a research project
(D) criticizing experimental results
(E) explaining the origin of certain scientific data

2. 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. - Correct "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 Line Mars's gravity by the impact on Mars of other meteorites."
(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.

3. 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. - Correct "Phinney estimates that the probability of these rocks hitting Mars is about one-tenth as great as that of Mars's rocks hitting Earth"
(E) The probability is less than the probability that a rock from Earth will escape Earth's gravity.

4. 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. - Correct, if 25% of the rocks are released in the same direction, the total probability will increase from 17/1000
(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

adstudy · Answer

1. The passage is primarily concerned with

Before going to the options, we should fairly get an idea of the primary point of the author. The crux of the passage is in the below sentence
"This conclusion has led to another  question : whether meteorite impacts on Earth have similarly driven rocks from this planet to Mars."

Lets move to the answer choices -

(A) presenting an argument to support a particular hypothesis

Nothing about a hypothesis. Passage is clearly mentioning the whole thing as a question.  A incorrect

(B) suggesting an answer to a theoretical question

Yes exactly, it is a question that a theoretical one as astronomer is just speculating.   B Correct

(C) questioning the assumptions of a research project

Nothing about a Project. Passage is clearly mentioning the whole thing as a question.   C incorrect

(D) criticizing experimental results

Nothing about any Experiment. Passage is clearly mentioning the whole thing as a question.   D incorrect

(E) explaining the origin of certain scientific data

Nothing about Scientific data. Passage is clearly mentioning the whole thing as a question.   E incorrect

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2. 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?

Okay, so the important phrase in the question is - 'presence on Earth of meteorites from Mars'. We find a direct reference of this in the 3rd and 4th line of the passage -
 "Martian origin might actually have been blasted free of Line Mars's gravity by the impact on Mars of other meteorites."

(A) A meteorite struck the Earth with tremendous velocity.

Does not match with the lines mentioned above.  A incorrect

(B) A meteorite collided with Mars.

Can be deduced from the above set of lines   B Correct

(C) Approximately 1,000 rocks were ejected from Mars.

Does not match with the lines mentioned above.  C incorrect

(D) The orbits of Earth and Mars brought the planets to their closest points.

Does not match with the lines mentioned above.  D incorrect

(E) Rocks from a meteorite impact broke free of Earth's gravity.

Does not match with the lines mentioned above.  E incorrect

*** In these type of questions, better to find the relevant points in the passage rather than jog through your memory. The answers are written in such a way that it might just confuse you on data points after a quick read of the passage.***

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3. The passage suggests that which of the following is true concerning the probability that a rock, if ejected from Mars, will hit the Earth?

The only place where probability is mentioned is in the following lines -
 "Phinney estimates that the probability of these rocks hitting Mars is about one-tenth as great as that of Mars's rocks hitting Earth." 
Now if we read the question carefully it asks us about the probability of rock hitting from Mars to Earth and not the other way around as mentioned in the lines. So keeping this in mind lets see out answer choices -

(A) The probability is increased when particles are ejected from Mars in random directions.

No mention / reference of this option in given relevant lines.  A incorrect

(B) The probability is increased by the presence of large craters on the surface of Mars.

No mention / reference of this option in the given relevant lines.  B incorrect

(C) The probability is decreased when Mars's orbit brings the planet close to Earth.

No mention / reference of this option in the given relevant lines.  C incorrect

(D) The probability is greater than the probability that rock from Earth will hit Mars.

Yes, this is what we were talking about.   D Correct

(E) The probability is less than the probability that a rock from Earth will escape Earth's gravity.

No mention / reference of this option in the given relevant lines.  E incorrect

-------------------------------------------------------------

4. Which of the following, if true, would cast most doubt on Phinney's estimate of the probability of Earth rocks hitting Mars?

This question is on similar lines as question 3. So the answer will also be around those lines -
 "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." 
Okay, so after understanding this, lets read through 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.

Probably yes, will mark if no better option present

(B) Approximately 100 meteorites large enough to make a noticeable crater hit the Earth each year.

This is based out of some other data point in the passage(irrelevant here. so we can eliminate at this point) and is not correct as well. 'Noticeable' is a subjective word. It can be anything between 1% to 99%. But in the para a definite value is given (]60 miles crater). Hence we can eliminate this option

(C) No rocks of Earth origin have been detected on Mars.

This does not cast doubt rather strengthens the astronomer's estimates. Hence can be eliminated

(D) The velocity of ' rocks escaping from Earth's gravity is lower than the velocity of meteorites hitting the Earth.

No direct of velocity anywhere in the relevant lines. Moreover no mention of it in the passage itself. Hence can be eliminated

(E) No craters more than 60 miles across have been found on Mars

Craters on Mars have not been talked about in the relevant lines. Hence can be eliminated
  Hence A

TheAdmissionHub · Answer

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 Line 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.
 
 What the author does: 
 The author explains  whether rocks from Earth can reach Mars after meteorite impacts  and uses Phinney’s computer simulation to show that the probability is very low.
 Summary: 
The author discusses whether meteorite impacts on Earth could send rocks into space and eventually to Mars. Astronomer S.A. Phinney explains that an extremely large meteorite would be needed to eject rocks from Earth’s gravity. He also estimates that the chance of these rocks reaching Mars is much lower than the chance of rocks from Mars reaching Earth. To support his idea, Phinney used a computer simulation with 1,000 particles and found that only 17 of them would hit Mars.
 
 1. The passage is primarily concerned with 
 
 (A):  WRONG:  The passage does not mainly try to defend a specific hypothesis. Instead, it introduces a theoretical question: if rocks can be ejected from Mars and reach Earth, could rocks from Earth also reach Mars?
(B):  CORRECT : This is the best answer. The passage presents the question and then gives Phinney’s estimate and computer simulation as an answer. The simulation showed that 17 out of 1,000 particles ejected from Earth would hit Mars, suggesting that it is possible but unlikely.
(C):  WRONG:  The author does not question the assumptions behind Phinney’s research. Instead, the passage reports and explains his calculations.
(D):  WRONG:  There is no criticism of the results. The author simply presents Phinney’s findings, including the result that 17 particles would reach Mars.
(E):  WRONG:  The passage does not focus on where scientific data came from. The data from the computer simulation are used to answer the theoretical question about rocks traveling from Earth to Mars.

2. 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):  WRONG:  The passage does not say that a meteorite striking Earth caused Martian meteorites to arrive on Earth. BUT the point is striking MARS
(B):  CORRECT:  The passage says that scientists believe meteorites from Mars may have been blasted free from Mars by the impact of other meteorites. Therefore, a meteorite colliding with Mars may have initiated the process.
(C):  WRONG:  The 1,000 particles were part of Phinney’s computer simulation. They were hypothetical particles, not actual rocks ejected from Mars.
(D):  WRONG:  The passage does not say that the orbits of Earth and Mars brought them to their closest points.
(E):  WRONG:  This refers to rocks being ejected from Earth, which is the opposite direction from the process being described. The question asks about the meteorites from Mars that reached Earth.
 
 3. 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):  WRONG:  The passage does not say that ejecting particles in random directions increases the probability. Random directions were only used in Phinney’s computer simulation.
(B):  WRONG:  The passage mentions that meteorite impacts can create large craters, but it does not say that large craters increase the probability of a rock hitting Earth.
(C):  WRONG:  The passage does not say that Mars being closer to Earth decreases the probability.
(D):  CORRECT:  The passage states that the probability of rocks from Earth hitting Mars is about one-tenth as great as the probability of rocks from Mars hitting Earth. Therefore, a rock ejected from Mars is more likely to hit Earth than a rock from Earth is to hit Mars.
(E):  WRONG:  The passage does not compare the probability of a rock hitting Earth with the probability of escaping Earth’s gravity.
Answer: A
 
 4. Which of the following, if true, would cast most doubt on Phinney's estimate of the probability of Earth rocks hitting Mars? 
(A):  CORRECT:  Phinney’s estimate is based on a computer simulation in which 1,000 particles were ejected from Earth in random directions. If, in reality, 25% of the particles go in the same direction, then the particles are not randomly distributed, so his estimate of the probability could be significantly wrong.
(B):  WRONG:  The number of meteorites hitting Earth each year does not directly challenge Phinney’s estimate of the probability that an ejected rock will hit Mars.
(C):  WRONG:  The fact that no Earth rocks have been detected on Mars does not necessarily disprove the estimate. The passage says that the probability is low, not impossible. 
(D):  WRONG:  The velocity of rocks escaping Earth’s gravity is not what Phinney’s estimate is mainly based on. His calculation concerns where particles go after being ejected.
(E):  WRONG:  The size of craters on Mars is not relevant to Phinney’s estimate. The passage is concerned with rocks being ejected from Earth, not Mars.

Recently some scientists have concluded that meteorites found on Earth

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Recently some scientists have concluded that meteorites found on Earth

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