While researching a topic, a student has taken the following notes:In astronomy, the mass of stars can be described in...
GMAT Expression of Ideas : (Expression) Questions
While researching a topic, a student has taken the following notes:
- In astronomy, the mass of stars can be described in units called solar masses.
- One solar mass is roughly equal to the mass of the Sun.
- The mass of the star Proxima Centauri is 0.122 solar masses.
- The mass of the star Sirius A is 2.063 solar masses.
The student wants to emphasize the mass of Sirius A. Which choice most effectively uses relevant information from the notes to accomplish this goal?
The mass of stars, like Proxima Centauri, can be described in units called solar masses.
In astronomy, the mass of stars can be described in units called solar masses, and one solar mass is roughly equal to the mass of the Sun.
The Sun is more massive than Proxima Centauri, which has a mass of 0.122 solar masses.
With a mass of 2.063 solar masses, Sirius A is more massive than the Sun.
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| 'In astronomy, the mass of stars can be described in units called solar masses.' |
|
| 'One solar mass is roughly equal to the mass of the Sun.' |
|
| 'The mass of the star Proxima Centauri is 0.122 solar masses.' |
|
| 'The mass of the star Sirius A is 2.063 solar masses.' |
|
Provide Passage Architecture & Core Elements
Main Point: The notes provide information about how astronomers measure star mass using solar masses as units, with specific examples of two different stars.
Argument Flow: The notes establish the measurement system (solar masses), define the unit (equal to Sun's mass), then provide concrete data points for two specific stars with very different masses.
Step 2: Interpret the Question Precisely
What's being asked? Which choice most effectively uses the research notes to emphasize the mass of Sirius A.
What type of answer do we need? A statement that highlights or draws attention to Sirius A's mass specifically.
Any limiting keywords? 'Most effectively' means we need the choice that best accomplishes the goal, and 'emphasize' means the focus should be on making Sirius A's mass stand out or seem significant.
Step 3: Prethink the Answer
- To emphasize Sirius A's mass, the right answer should:
- Include the specific mass measurement for Sirius A (2.063 solar masses)
- Make Sirius A the main focus of the sentence
- Show why this mass is significant or notable (like comparing it to something familiar)
- From our notes, we know that one solar mass equals the Sun's mass, so Sirius A at 2.063 solar masses is more than twice as massive as our Sun. This comparison would make the mass seem more impressive.
The mass of stars, like Proxima Centauri, can be described in units called solar masses.
✗ Incorrect
- Focuses entirely on Proxima Centauri, not Sirius A
- Doesn't mention Sirius A at all
- Fails to accomplish the goal of emphasizing Sirius A's mass
In astronomy, the mass of stars can be described in units called solar masses, and one solar mass is roughly equal to the mass of the Sun.
✗ Incorrect
- Simply explains the measurement system in general terms
- Doesn't mention any specific star
- Provides no emphasis on Sirius A whatsoever
The Sun is more massive than Proxima Centauri, which has a mass of 0.122 solar masses.
✗ Incorrect
- Focuses on comparing the Sun to Proxima Centauri
- Completely ignores Sirius A
- Doesn't accomplish the stated goal
With a mass of 2.063 solar masses, Sirius A is more massive than the Sun.
✓ Correct
- Places Sirius A as the main subject of the sentence
- Includes the specific mass measurement (2.063 solar masses)
- Creates a comparison that emphasizes how massive Sirius A is by stating it's 'more massive than the Sun'
- This comparison makes Sirius A's mass seem significant and impressive