Since I started writing an explanation with question #4, I figured I might as well go all the way...We're forming a five-rockstar basketball team out of a pool of 7 talented recording artists/reality television stars:
4 males (which I'll symbolize as
m n p o)
3 females (symbolized as
R S T)
and putting those five into three positions: two forwards (f), one center (c), and two guards (g).
R1: Either both starting guards are women, or neither starting guard is a woman.
R2: Either both starting forwards are men, or neither starting forward is a man.So no co-ed guard or forward duos: either both guards are ladies, or both are dudes, and the same goes for the forwards.
R3: Neither Ronnie Spector nor Stevie Nicks starts at center.The only possible female center is Tina Turner. (Natch!)
R4: Neither Ozzy Osbourne nor Neil Young starts at forward.Good choice: neither one can focus their eyes enough to see the basket. However, combining this with rule 2 implies either our forwards are m(f) and p(f), or they're two of the women.
R5: If Tina Turner starts at center, Ozzy Osbourne starts at guard.Ozzy might be drugged out of his mind, but he's cagey enough to make a great point guard. This is pure formal logic:
T(c) --> o(g)
not o(g) --> not T(c)Now to the questions!
1. Which one of the following could be a correct assignment of players to starting positions?
(A). Take the rules and apply them to the choices, eliminating them one by one.
R1: Either two dude guards, or two lady guards. This gets rid of...
(E)
R(g) o(g) m(f) p(f) T(c)R2: Only women forwards or only male forwards. This gets rid of...
(B)
R(g) S(g) m(f) T(f) p(c)R3: Ronnie and Stevie are never center. This doesn't get rid of anything.
R4: Neither Ozzy nor Neil can be forwards. This cuts out...
(D)
o(g) p(g) m(f) n(f) T(c)R5: If Tina's a center, Ozzy's a guard. This eliminates...
(C)
p(g) n(g) R(f) S(f) T(c)That only leaves choice A:
(A)
R(g) S(g) m(f) p(f) o(c)2. If Stevie Nicks starts at forward, which one of the following must be false?
(E). If we have one female forward, we have to have two (R2), thus the other one is either R or T. Since we'll only have one female left, we then have to have two male guards (R1).
♂(g) ♂(g) S(f) R/T(f) ?(c)
Thus, (E) is impossible: Ronnie is female (and how! a headshot from 1967:
http://is.gd/5fEYO)
3. Which one of the following pairs of assignments would determine the assignment of the remaining positions?
(D). This question is asking if we could infer enough to fill up the entire team by knowing two players' positions. I want to start this question by testing the most likely choices: since the rule that gives the most direction is rule 5, I'll test the two choices with Tina as center first.
(C) If Tina's center, Ozzy is a guard. The forwards, though, could be either Ronnie and Stevie, or Mr. Stipe and Prince. This doesn't fill up the roster.
(D) Again: if Tina's center, Ozzy's a guard. If Michael's a forward, we need another male forward (R2), and it can't be Ozzy or Neil (R4). Thus, the only option is Prince. Last but not least, if we have one male guard in Ozzy, we have to have another, and only Neil is left. This one works!
o(g) n(g) m(f) p(f) T(c)4. Which one of the following, if substituted for the restriction that if Tina Turner starts at center, Ozzy Osbourne starts at guard, would have the same effect on determining who will start?
(D). Our goal is to find a rule equivalent to rule 5. To review R5:
T(c) --> O(g)
not O(g) --> not T(c) We want a rule that will have the same effect -- in short, intuition suggests we might want to find something pretty close to the contrapositive. (D) says:
not O(g) --> not R(c) and not S(c) and not T(c)Combining that with rule 3 means that choice (D)
is the contrapositive we were looking for.
The others:
(A) says something self-evident: if someone is in a slot, no one else is in that slot. Not useful.
(B) Formally logically:
R(g) or S(g) or T(g) --> not T(c)
T(c) --> not R(g) and not S(g)...however, if Tina is a center, Ozzy doesn't have to even play! Remember, if I want the same effect as rule 5, I want to know that if Tina's center, Ozzy's a guard; and if Ozzy's not a guard, Tina can't be center.
Need proof? with this rule, the following situation could be possible:
R(f) S(f) T(c) m(g) p(g)(C) Again, some
logique formelle:
R(g) or S(g) or T(g) --> not O(g)
O(g) --> not R(g) and not S(g) and not T(g) That doesn't bring about the same effect as rule 5. If this new rule is in play, if Tina is center, Ozzy doesn't have to be guard.
m(f) p(f) T(c) R(g) S(g)(E) To rely upon Rule 3 again, if a woman starts at center, that lady's name is Tina Turner (Proud MARY!). Thus, I'll substitute her in to this rule:
T(c) --> n(g)
not n(g) --> not T(c)Again, Tina can be center without any obligation for Ozzy to even play:
R(f) S(f) T(c) n(g) m(g)5. Which one of the following could be true?
(C). The first two of these might jump out as being impossible, numbers-wise:
(A) doesn't work: if we have one woman, she has to be center (any other single lady must be paired up to play forward or guard: Beyonce isn't part of this game.)
(B) is impossible: if we have two women play, and Tina is center, we only have one other woman -- and we need a pair to play either forwards or guards.
But then we hit pay dirt:
(C) If Tina is guard, that means the other guard is Ronnie or Stevie. With two of the female players accounted for, we must have two males be forwards, and as per rule 4, neither Ozzy nor Neil can play forward, and thus the forwards must be Michael and Prince. For center, we have Neil or Ozzy:
m(f) p(f) n/o(c) T(g) R/S(g)The other two don't work at all.
(D) If we have three women, and Tina's a guard, Ronnie or Stevie will end up as a single lady: and since neither of them could be center, this won't work.
(E) If Michael's a forward, then Prince is too (R2 and R3); with three women, we end up in the same situation as we did in (D).
6. If Ronnie Spector starts at guard, how many different starting line-ups are possible?
(B). If Ronnie's a guard, then either Stevie or Tina is a guard, too. This means we have male forwards, and only Michael and Prince can fit that bill. Thus, for center we've got Neil or Ozzy (but not Tina: since Ozzy's not a guard, we can't have Tina as center):
m(f) p(f) n/o(c) R(g) S/T(g)
This gives us four possibilities, or choice (B).
7. If the tournament decides to change the rules and require the team to add a sixth starter"”a second center who must be female"”and all the other rules remain in effect, which one of the following must be false?
(C). This adds a wrinkle, but nothing serious (although it's arguable this would ruin the entire game of basketball). The only center who can be female is Tina, so we have Ozzy as a guard, and one of the other men as the other guard. Moreover, since Tina was the only possible female center, that means the other center has to be male. That makes for three males assigned (two guards, and one center), and because we only have one male left over, the remaining females (Ronnie and Stevie) have to be forwards:
R(f) S(f) T(c) ♂(c) o(g) ♂(g)
A quick scan shows us that (A) is possible, and (B) is necessary; however, a quick scan of our setup shows that (C) isn't possible at all!
BONUS QUESTION:
8. Which ridiculous diva-quality demand in the contract rider will make it so no team can possibly be formed?
(A) Ozzy and Neil cannot be on the team together (will wander off behind the bleachers).
(B) Ronnie must be on the team, but refuses to be on the team with Tina (due to a long-standing argument about Phil Spector).
(C) If Stevie is included on the team, neither Ozzy must not be included (danger of relapse).
(D) Females must play guards, and neither Ozzy nor Neil can be center (Prince's whims).
(E) No females can play forwards or guards (Ozzy didn't feel comfortable with it).
The answer is (D): the other choices work out just fine. So if we have female guards, we have to have male forwards (R2); if we have male forwards, they've got to be Michael and Prince (R4). If that's the case, none of the three players left to play center don't work: Ozzy or Neil (nope! can't be center, so the answer choice says) or Tina (the only possible female center -- but she won't work because of the contrapositive of R5).
(A) It's not so difficult to leave one of them out of the team altogether, and we'll be fine.
m(f) p(f) o(c) S(g) T(g)(B) There's got to be a story there, but if Ronnie is a forward with Stevie this works fine.
R(f) S(f) o(c) n(g) p(g)(C) Sensible, and not terribly restrictive. Here's one way it can play out:
R(f) S(f) T(c) m(g) p(g)(E) This works out okay:
m(f) p(f) T(c) o(g) n(g)