Question 2·Medium·Rhetorical Synthesis
While researching a topic, a student has compiled the following notes:
- The average cost of solar-generated electricity has fallen by 85% since 2010.
- Solar electricity now averages about $0.04 per kilowatt-hour (kWh).
- The cost of coal-generated electricity has remained relatively unchanged at about $0.06 per kWh.
- Global solar installations have grown roughly 25% each year for the past decade.
The student wants to emphasize that solar power has become less expensive than coal power. Which choice most effectively uses relevant information from the notes to accomplish this goal?
For rhetorical synthesis questions, start by underlining the goal stated in the prompt (for example, “emphasize that X is cheaper than Y”). Then quickly scan the notes and mark only the details that directly serve that goal (here, the specific prices for solar and coal). Finally, eliminate any answer choices that (1) ignore those key details, (2) add information that doesn’t address the stated goal (like popularity or growth alone), or (3) talk about only one of the things that are supposed to be compared. This targeted approach keeps you from being distracted by interesting but irrelevant statistics.
Hints
Restate the goal
Focus on the exact goal: the student wants to show that solar power has become less expensive than coal power. Which choices actually talk about price differences between the two?
Look for a direct comparison
From the notes, which two numbers let you compare solar and coal right now? Look for the answer choice that uses both of those prices in the same sentence.
Ignore unrelated but interesting details
Some notes are about how fast solar is growing or how much its price has dropped over time. Those are interesting, but which detail proves that solar is currently cheaper than coal?
Step-by-step Explanation
Identify the writing goal
The prompt clearly states the student’s goal: to emphasize that solar power has become less expensive than coal power.
So, the correct choice must:
- Talk about cost, not popularity or growth alone.
- Show that solar is now cheaper than coal, not just that its price changed over time.
Decide which notes are most relevant
Look back at the bullet-point notes and ask: which details directly prove that solar is now less expensive than coal?
The key notes are:
- "Solar electricity now averages about $0.04 per kilowatt-hour (kWh)."
- "The cost of coal-generated electricity has remained relatively unchanged at about $0.06 per kWh."
These two numbers allow a direct price comparison between solar and coal right now.
Match the answer choice to the goal and key notes
Now scan each option and see:
- Does it mention cost for both solar and coal?
- Does it focus on current prices, not just trends or popularity?
- Does it clearly show that one is cheaper than the other?
Only one option both:
- Uses the actual prices from the notes (0.06 per kWh), and
- Explicitly states that solar has become the cheaper source of electricity.
That option is: “Solar power, now averaging about 0.06—has become the cheaper source of electricity.”
Confirm why other options don’t work
Check the remaining options:
- One mentions only coal’s cost, not solar, so it cannot show that solar is cheaper.
- Another explains that solar costs fell and installations grew, but it doesn’t compare solar’s cost to coal’s.
- The last one talks about consumer preference and installation growth, not price at all.
Therefore, the sentence that directly compares the current prices (0.06) and states that solar is now the cheaper source is the correct answer: “Solar power, now averaging about 0.06—has become the cheaper source of electricity.”