Q8

[esthertan0310]

I can see why D and E are wrong. I can also see why C is correct, but I don't know why A and B is wrong. Wouldn't these arrangements be possible?

A.

J F/H F/H R
J F/H F/H R

B
J F H R
J F H R

Thanks!

[ohthatpatrick]

Your examples definitely could be true. They don't violate any rules.

Quick detour though ...

Which one of the following must be true?

(A) The first name of any US President must begin with a 'B'

Is (A) correct because Barack Obama is a US President?


Of course not. George Washington is a way to disprove this answer.

Remember, any time you're judging Must Be True ideas, you're NEVER concerned with whether it COULD be true. Thus, you're never testing what the answer choice actually describes.

You're testing to see whether you can come up with a COUNTERexample to what is described.

The opposite of
Must Be True
is
Could Be False

So to get rid of four answers, you'd have to show that they all could be false.

Must Be True = Unavoidable
Could Be False = Avoidable

Looking at (A), we would ask ourselves, "If I put two sides of J on tape 1, can I avoid rock on tape 4?"

Yes.

J R H F
J R H F

Eliminate.

Looking at (B), we'd ask ourselves, "If I put two F's on tape 2, can I avoid having H on tape 3?"

Yes.

J F R H
J F R H

Eliminate.

Hope this helps.