Question 95·Medium·Rhetorical Synthesis
While researching a topic, a student has taken the following notes:
- The Hubble Space Telescope (HST) was launched in 1990 and orbits Earth roughly every 95 minutes.
- A 1993 servicing mission corrected the telescope’s optics, dramatically improving image quality.
- By observing Cepheid variable stars in distant galaxies, HST helped refine the value of the Hubble constant (the rate at which the universe expands).
- The refined constant allowed astronomers to estimate the universe’s age at about 13.8 billion years.
- HST has also produced famous deep-field images, revealing thousands of previously unseen galaxies.
The student wants to emphasize the Hubble Space Telescope’s contribution to determining the age of the universe. Which choice most effectively uses relevant information from the notes to accomplish this goal?
For rhetorical synthesis questions, underline the specific goal in the question stem, then select only the notes that directly serve that goal. Choose the option that accurately combines those notes into a clear cause-and-effect statement, and eliminate options that emphasize interesting but off-goal details (dates, orbit time, image quality) or that leave out a required link in the chain.
Hints
Clarify the task
Focus on the phrase “contribution to determining the age of the universe.” Which notes describe a measurement that leads to an age estimate?
Find the key chain of ideas
Look for a sequence like: what Hubble observed → what value was refined → what that refinement allowed astronomers to calculate.
Eliminate off-goal details
Choices that focus mainly on orbit time, repairs, or image quality (without tying to an age estimate) won’t best meet the goal.
Step-by-step Explanation
Identify the goal
The student wants to emphasize the Hubble Space Telescope’s contribution to determining the age of the universe. So the best sentence should focus on the notes that explain how Hubble’s work led to an age estimate, not just on repairs, orbit time, or impressive images.
Select the relevant notes
The notes that directly support the goal form a cause-and-effect chain:
- Hubble observed Cepheid variable stars in distant galaxies.
- Those observations helped refine the Hubble constant (expansion rate).
- The refined constant allowed astronomers to estimate the universe’s age at about 13.8 billion years.
Choose the option that matches that chain
Pick the choice that links (1) Cepheid observations to (2) refining the Hubble constant and (3) estimating the universe’s age (about 13.8 billion years). The correct answer is:
The Hubble Space Telescope observed Cepheid variable stars in distant galaxies, helping refine the Hubble constant and enabling an estimate of the universe’s age of about 13.8 billion years.