Need help with a LG question: December 2006 Questions 11-15 Forum

[apollo13]

December 2006 Questions 11-15 (its from PowerScore LG Bible PAGE 159)
The book does explanations to each questions but I still DON'T GET IT! Please help a 0L out...

Question goes:
A locally known guitarist's demo CD contains exactly seven different songs - S, T, V, W, X, Y, and Z. Each song occupies exactly one of the CD's seven tracks. Some of the songs are rock classics, the others are new compositions.
Conditions as follow- S occupies the fourth track of the CD. Both W and Y precede S on the CD. T precedes W on the Cd. A rock classic occupies the sixth track of the CD. Each rock classic is immediately preceded on the CD by a new composition. Z is a rock classic.

According to the book's solution, the diagram set up for Song is:
(T>W,Y) S (V, X, Z)
1 2 3 4 5 6 7

My first question here is that obviously, I know that T W Y cannot be placed in 5,6, 7 but there's a possibility of V X Z being included in 1 2 3 sequencing. Why can't V X Z be also placed in 1 2 3?

Also: The rule #5 explains: R -> NR
and thus the book sequences Type as: N _ _ _ N R N
Why is this the case? I know 1 is N because through Now Laws rule R comes off in 1 making N, but why is 7th N? Can't that be also R? When I first solved this, I just put all the sequencing as N _ _ _ N R _
because the rule clearly says that whenver there is R it's N preceding R so 7 is empty because the rule is irrelevant to 7 since it doesn't talk about what comes after R

Yea, pretty frustrated... Help me out guys
Thanks a bunch

[I, Lawyer]

December 2006 Questions 11-15 (its from PowerScore LG Bible PAGE 159)
The book does explanations to each questions but I still DON'T GET IT! Please help a 0L out...

Question goes:
A locally known guitarist's demo CD contains exactly seven different songs - S, T, V, W, X, Y, and Z. Each song occupies exactly one of the CD's seven tracks. Some of the songs are rock classics, the others are new compositions.
Conditions as follow- S occupies the fourth track of the CD. Both W and Y precede S on the CD. T precedes W on the Cd. A rock classic occupies the sixth track of the CD. Each rock classic is immediately preceded on the CD by a new composition. Z is a rock classic.

According to the book's solution, the diagram set up for Song is:
(T>W,Y) S (V, X, Z)
1 2 3 4 5 6 7

My first question here is that obviously, I know that T W Y cannot be placed in 5,6, 7 but there's a possibility of V X Z being included in 1 2 3 sequencing. Why can't V X Z be also placed in 1 2 3?

Also: The rule #5 explains: R -> NR
and thus the book sequences Type as: N _ _ _ N R N
Why is this the case? I know 1 is N because through Now Laws rule R comes off in 1 making N, but why is 7th N? Can't that be also R? When I first solved this, I just put all the sequencing as N _ _ _ N R _
because the rule clearly says that whenver there is R it's N preceding R so 7 is empty because the rule is irrelevant to 7 since it doesn't talk about what comes after R

Yea, pretty frustrated... Help me out guys
Thanks a bunch

For the first part, since S is fixed in the fourth spot and there are three variables that must come before S (T,W,Y) V,X and Z must be in the final three spots. For V X or Z to be in spots 1, 2, or 3, T,W, or Y would have to be in either 5, 6, or which is after S. That would then violate that T, W and Y cant be in 5, 6, or 7.

For the second part, either it is N or its is R in the seventh spot. For it to be R, the sixth spot would have to be N. Since the sixth spot is R, the seventh spot cannot be R. The only other option is N, so the seventh spot has to be N.

Hope this helps.