Q14 - Among a sample of diverse

[ManhattanPrepLSAT1]

For this one you need to be able to either reason strongly or know how to use formal logic.

There are four objects that can be on the face of a coin: a judge’s head, an explorer’s head, a building, or a tree. No coin has a head on both faces, and if a coin has a judge’s head on one side, then it has a tree on the other. Now we just have to find something that must be true.

(A) is not necessarily true. If a coin has an explorer’s head on one side, it still could have a tree on the other side.
(B) is not necessarily true. We cannot have a head on both faces, but we can have a building and a tree.
(C) is not necessarily true. We could have a tree on one side and an explorer’s head on the other.
(D) must be true. Any coin with a judge’s head on one side must have a tree on the other, so it’s not possible for a coin to have a judge’s head on one side and a building on the other.
(E) is not necessarily true. Any coin with an explorer’s head is free to have a building on the other side.

[JonT]

::facepalm::

Forgot about that constraint - thanks!

[nflamel69]

ahhh!!! I didn't read the question more carefully. I kept thinking what if the sample is not representative of the population! then none of them has to be right! Grr...

[mitrakhanom1]

I am confused between B and D. So B says if you have a tree on one side then you have a judge's head on the other. But our constraint says that all coins with a judge's head on one side have a tree on the other. So answer choice B can't be right because we can have a tree on one side and something else like a building on the other side. Right? And D is saying If you have a building on one side then you don't have a judge's head on the other. Doesn't that mean on the flip side of the building can be either an explorer's head or a tree? So does that mean if you pick up a coin on its building side the other side cannot be a judge's head? I thought if you pick a coin and first on one side its a judge's head then the other side must be a tree. Does the order you look at either side of a coin matter? I think I'm confusing the order of what happens maybe.

[maryadkins]

I am confused between B and D. So B says if you have a tree on one side then you have a judge's head on the other. But our constraint says that all coins with a judge's head on one side have a tree on the other. So answer choice B can't be right because we can have a tree on one side and something else like a building on the other side. Right?

Yes.

And D is saying If you have a building on one side then you don't have a judge's head on the other. Doesn't that mean on the flip side of the building can be either an explorer's head or a tree?

Yes.

So does that mean if you pick up a coin on its building side the other side cannot be a judge's head? I thought if you pick a coin and first on one side its a judge's head then the other side must be a tree. Does the order you look at either side of a coin matter? I think I'm confusing the order of what happens maybe.

That's right. It cannot have a judge's head on one side if it has a building on the other. The order you look at the coin doesn't matter. Every coin with a judge's head on one side has to have a tree on the other.

[smsotolongo]

In answer B, isn't the logic reversed? If A -->B, we can't assume that B -->A.

[tuf58975]

I got this wrong without noticing the restrains Shouldn't done this wrong.