Logical Reasoning

PT128 · S3 · Q2 Because metallic mirrors absorb some

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Because metallic mirrors absorb some light, they waste energy.

Conclusion: As a result

Metallic mirrors cannot be used in applications in which minimizing energy loss is important.

Evidence: Because

Metallic mirrors absorb some light.

When light strikes a metallic mirror, electrons in the mirror move, using energy and dimming the reflected image.

Intermediate Conclusion

They (metallic mirrors) waste energy.

Evaluate

In most Main Conclusion questions, the main conclusion is somewhere in the first few lines of the argument, typically with no conclusion indicator words to draw you in. That trend makes it easy to mistake the Intermediate conclusion in this argument for the Main Conclusion. But if you look at the structure language that connects the second sentence to the third (As a result), you can see that claim three follows from claim two. It also seems to follow from claim one, but if you're unsure about that, you can try the Support test.

Metallic mirrors waste energy. Why? Because metallic mirrors cannot be used in applications in which minimizing energy loss is important.

That doesn't make a lot of sense.

Metallic mirrors cannot be used in applications in which minimizing energy loss is important. Why? Because metallic mirrors waste energy.

Much better.

Goal

Find an answer that paraphrases the final claim. It may or may not include the example of high-powered lasers, since that's essentially a clarifying example given to show the reader what types of applications require minimizing energy loss.

2.

Which one of the following most accurately expresses the argument's main conclusion?

  1. Metallic mirrors reduce the effectiveness

    Inference Bait

    This is an inference that we could draw, not the conclusion the argument did draw.

    3% picked this

  2. Part of the light falling

    Premise

    This is a paraphrase of the first half of the first sentence, which is a premise.

    1% picked this

  3. High-powered lasers require mirrors that

    Inference Bait

    This claim is well supported (though not entirely supported) but the argument, but it's not the argument's explicitly stated conclusion. That makes it Inference Bait. It's well supported because high-powered lasers were given as an example of the type of application for which conserving energy is important. It isn't 100% supported, though, because we don't actually know whether high-powered lasers require the use of mirrors at all.

    1% picked this

  4. A tendency to waste energy

    Out of Scope: most significant disadvantage

    This isn't explicitly stated in the argument so it can't be the correct answer. The argument isn't concerned with naming the most significant disadvantage of metallic mirrors.

    4% picked this

  5. Correct

    Metallic mirrors are unsuitable for

    Why this is right

    This is a good paraphrase for "metallic mirrors cannot be used in applications in which minimizing energy loss is important."

    Skill tested: Main Conclusion · how this choice captures the argument's function is the move to repeat next time.

    91% picked this

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