LSAT 134 – Section 3 – Question 13

LSAT 134 - Section 3 - Question 13

October 2011

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT134 S3 Q13
+LR
Resolve reconcile or explain +RRE
Math +Math
A
87%
165
B
1%
155
C
2%
158
D
7%
157
E
3%
157
136
145
155
 +Medium 146.872 +SubsectionMedium

Astronomers have found new evidence that the number of galaxies in the universe is not 10 billion, as previously believed, but 50 billion. This discovery will have an important effect on theories about how galaxies are formed. But even though astronomers now believe 40 billion more galaxies exist, many astronomers’ estimates of the universe’s total mass remain virtually unchanged.

"Surprising" Phenomenon
Why did discovering so many new galaxies not change astronomers’ estimates of the universe’s total mass?

Objective
A hypothesis resolving this discrepancy must give information about the way astronomers calculate the total mass of the universe. It will imply that some property of the new galaxies kept astronomers from remaking their mass estimates, or that astronomers’ estimates depend little on the number of galaxies.

A
The mass of galaxies is thought to make up only a tiny percentage of the universe’s total mass.
This explains why the astronomers did not revise their mass estimates by much. If a large majority of the universe’s mass is not contained in galaxies, then finding new galaxies would not be cause to update the mass measurement by a significant amount.
B
The overwhelming majority of galaxies are so far from Earth that their mass can be only roughly estimated.
This does not explain why astronomers chose not to update their mass estimates. If the masses of the new galaxies can at least be estimated, their mass should have been added to estimates of the total mass of the universe.
C
The number of galaxies that astronomers believe exist tends to grow as the instruments used to detect galaxies become more sophisticated.
This gives context for the astronomers’ discovery, but does not explain why they opted to keep their current mass estimates. If astronomers routinely discover new galaxies, their estimates of the universe’s mass should also be updated routinely.
D
Theories about how galaxies are formed are rarely affected by estimates of the universe’s total mass.
This is irrelevant information. Astronomers did not update their estimates of the universe’s total mass, so theories about galaxy development would not have been so affected anyway.
E
There is no consensus among astronomers on the proper procedures for estimating the universe’s total mass.
This does not state that some astronomers disregard the number of galaxies when estimating the universe’s total mass. Whatever their methods, their decision not to update their measurements is a mystery.

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LSAT PrepTest 134 Explanations

Section 1 - Logical Reasoning

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Reading Comprehension

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