by ManhattanPrepLSAT1 Thu May 06, 2010 1:36 am
I'd be happy to point out what's going on with each of the incorrect answers that you're having issues with. If for some reason this doesn't seem to match what you have as you set up each question, maybe you could post your setup and we could work it through together.
7. answer choice (C) has three sides of jazz, but there are supposed to be only two sides of each kind of music.
8. (C) Must be true. Look at the fourth constraint. It could be written out
R(1) --> ~F(2)
R(2) --> ~F(3)
R(3) --> ~F(4)
If there are two sides of rock on side two then there cannot be any folk on tape three
_ R _ _
J R _ _
1 2 3 4
There can be one side of folk on tape one, but no matter what, at least one side of folk will have to be on tape four.
9. To see why answer choice (A) should be eliminated
J _ _ F
J _ _ H
1 2 3 4
Where do you want to put the rocks? We cannot put them on tape three and if we put them on tape two, then the other folk will follow and break the last constraint.
(C) can be eliminated because of the following
_ _ F J
J _ F R
1 2 3 4
Now, we cannot put the second rock anywhere. Rock is precluded from the first tape by the first constraint and from the second tape by the fourth constraint.
(D) can be eliminated because of the following
_ _ _ F
J _ J F
1 2 3 4
The problem here is that only hip-hops and rocks are left but neither are permitted on tape one.
11. (B) cannot be true for the following reason
_ H R _
J H R _
1 2 3 4
There will be at least one folk on tape four and this will break the fourth constraint.
I really hope this helps. Another thing to keep in mind is that while working from wrong to right is the correct approach for logical reasoning, it's not the way you want to go in logic games. Run with chains of inferences. I rarely check every answer choice on a logic games question.