LSAT 137 | Section 3 | Logical Reasoning: Q10

LR Question 10 Explanation

QUESTION TEXT: A ring of gas emitting X-rays flickering 450 times per…

QUESTION TYPE: Most Strongly Supported

FACTS:

1. A gas ring flickers 450 times per second. It is orbiting a black hole.
2. According to widely accepted theory, this means that the gas ring must be 49 km in diameter.
3. If this is so, the black hole must be spinning.

ANALYSIS: The question stem actually adds an additional fact: assume the theories are correct.

That makes things easy. If the theories are correct, then the black hole must be spinning.

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1. We don’t care about black holes with gas rings of other diameters. We only care about this black hole, and gas rings with diameters of 49 km.
2. What a silly answer. We have no idea what things emit flickering X-rays. Maybe those X-rays are really common! Maybe humans emit flickering X-rays. Who knows?
3. CORRECT. If the theories are correct, the only way for the ring to be stable at 49 km is for the black hole to be spinning.
4. We have no info about why a black hole spins. We only care about whether it spins.
5. Same as B. There could be a million reasons why a black hole is stationary. We have no evidence for this answer.