I will answer and supply my thinking to 19-24:
19. Correct list? We use the rules to eliminate incorrect answer choice
(A) Incorrect: N without J
(B) Correct Answer
(C) Incorrect: J with M
(D) Incorrect: X and P cannot be selected together
(E) Incorrect: X and Z cannot be selected together
20. If J,K,N,O,Y, and Z with N being first, which CANNOT be on the second Sunday?
You should sketch this out: notice that J and O rule is in effect here,
Thus if N is first then O can't be second because J is selected, thus O can not be slotted on the second Sunday.
(C)
21. If J,O,Y are in the first three Sunday, not necessarily in that order, which can not be slotted in the 5th Sunday?
You should sketch this one: How ironic that it builds of the last question (# 20).
If J and O are in, we know that J is ahead of O. Thus only J and Y can go first. Combine this with the other rule it invokes (X5th----> M/N/O1st ) and analyze it, the contrapositive gives us the answer, i.e. because M/N or O can be slotted first X can not be fifth. Look for X in the answer choices:
(E) Correct Answer
22. If O is on the first Sunday, which one of the following must also be selected?
How cool is this, the third question that focuses on J and O: This one needs no sketch, but it doesn't hurt. If O is the first then we know J is
not selected. Well if J is not selected rom Giuliani group, then the other two must be selected (H and K), look for one of the two:
(B) Correct Answer
23. Which one of the following must be selected:
Like taking candy from a baby: I need not explain. If you didn't figure this out during the set-up, no worries, just look at the impact of X
and Z in Vivaldi's group (X and Z can not both be selected via rule 3).
D. Correct Answer
24. Which CANNOT be selected with N?
This one requires you to connect two rules: then N---> J with, J or M ---> ~M. Hence, if J or M is selected then M can not be selected. And
via the contrapositive, if M is selected then J and M cannot be selected. Consequently N and M can not never be selected together.
What's key here is to notice that J or M negates M, both could negate M, but they need not. In other words, If N is selected has no effect on
O, thats why O is among the answer choices.
(A) Correct Answer
If anyone has a question, I welcome it with alacrity, so please ask!