PT16.S3.Q17 - silencing device for vacuums

moonstars5678

Can someone validate my reasoning for why A is right and E is wrong (I had originally picked E):

Stim:
The new device can just cancel out the noise that the vacuum makes, so because of this, this new device can operate more efficiently/use less electricity than the old-school silencers. Why?

A:
Historically, there's been a tradeoff between silencing noise and efficiency, so for the old-school silencers, having to design that requires using comparatively more energy.

E:
This only refers to silencers in general and how they make cleaners less efficient, so we don't actually know what the difference is between these new silencer devices vs the old-school silencers.

help

mesposito886

I think you pretty much nailed the reason why answer choice A is right above. Before the new device, vacuums that had silencers also had motors that were less efficient, which means they were using more energy. The new device bypasses this compromise, making these vacuums more energy efficient.

Answer choice E isn't as relevant as you might think; old silencers making vacuums heavier and less mobile doesn't really relate to energy consumption - it just sounds like they were cumbersome to use.

moonstars5678

Thanks @mesposito886! Would it not be fair to make the assumption that "heavier and less mobile" would mean it was less energy efficient (aka consumed more energy)? I'm having trouble identifying which assumptions are logical to make in RRE ACs and which are not.

mesposito886

@moonstars5678
No problem. The fact that A explicitly uses the word "efficient" tipped me off to its being the correct answer. In technical usage, efficiency usually implies a relationship between output produced and energy consumed, so I found it was more directly related to what the stimulus was saying.