PT16.S3.Q17 - Silencing Device

Broccoli

Question type: Explain

Premise:
1. There's a new silencing device that eliminate the noise the appliance makes
2. It's different from conventional silencers.

Conclusion:
1. The new device will operate with lower electric consumption than conventional vacuum designer.

I chose (B) thinking that the silencer will "share" the power with appliance. I realized that was just an assumption I made. It would actually not explain why the new silencing device will make lower electricity consumption because they are both using same power supply.

Anyways, I don't see why (A) is a correct answer. I'm not sure where to know that the motor's efficiency = electricity consumption

FixedDice

I'm not sure where to know that the motor's efficiency = electricity consumption

One of those things test writers assume will be implicitly understood by reasonable, college-educated test takers, I suppose.

(A) says that prior to the advent of the new silencing device, motor efficiency was sacrificed in favor of noise reduction. Stimulus says that the new silencing device will actively cancel out noises.

If the new silencing device reduces noises, then vacuum cleaners no longer need to reduce noise by sacrificing motor efficiency. So vacuum cleaners equipped with the new silencing device would be more efficient, which means less electricity consumption.

Broccoli

@FixedDice Thanks for the reply. Could you explain your first sentence to me? What are you really trying to say? We're all reasonable, college educated test takers here studying for this exam. Those reasonable, college educated test takers can make obvious mistakes but we're all here to learn. Your first sentence was really unnecessary.

Broccoli

#help

CoraMint

I agree that efficiency isn't directly tied to electricity consumption in the passage, but I think it's a reasonable inference. When I saw A, I just assumed that a motor that was less "efficient" would have to 1) run for longer to get the same work done compared to a more efficient motor, or 2) use more power to get the same work done in the same amount of time. Either would result in more electricity.

You could also confirm this inference via process of elimination:
B - No. At best, this would mean the new vacuum + device is using the same amount of power as before. At worst, it's using even more power. Doesn't explain the phenomenon.
C - No. Doesn't tell us anything about the new device.
D - No. Governmental standards are irrelevant to the actual amount of power used.
E - No. We don't know what heaviness/mobility have to do with electricity consumption. If anything, I would guess that a heavier/less mobile vacuum has to use more energy.

Broccoli

@"Tyler M." Right.. PoE did left me with A but I was just questioning myself too much. I'll make those inference next time.

FixedDice

@Broccoli180 said:
@FixedDice Thanks for the reply. Could you explain your first sentence to me? What are you really trying to say? We're all reasonable, college educated test takers here studying for this exam. Those reasonable, college educated test takers can make obvious mistakes but we're all here to learn. Your first sentence was really unnecessary.

Sorry if that part sounded obnoxious or cocky. I was responding to

I'm not sure where to know that the motor's efficiency = electricity consumption

this part right here. It isn't really explicitly written out in the stimulus; a candidate would have to rely on what he or she learned up to his or her undergraduate education (or graduate education if he or she received graduate education, homeschooling if he or she was homeschooled... but I digress).