If Kate is scheduled for Wednesday, which one of the following could be true?
Trey-EllingtonFebruary 7, 2020
How can Iris goes on Monday?
According to the rule and contrapositive, Iris cant go on Monday if Nancy isnt on Tuesday. In the question, Victor is on tuesday and Nancy is on Thursday, so how does that work?
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I think you've accidentally made a mistaken negation error. Remember for the contrapositive we have to reverse and negate. With what you wrote above, it looks like you may have forgotten to reverse.
The rule says "If Nancy is scheduled for Tuesday, Iris is scheduled for Monday." The contrapositive of that rule, then, is: If Iris is not scheduled for Monday, then Nancy is not scheduled for Tuesday."
Saying "if Nancy isn't on Tuesday, Iris can't go on Monday" is mistaken negation. That's incorrect because if Nancy isn't on Tuesday, we don't actually know what happens. The rule only addresses what happens when Nancy IS on Tuesday. If Nancy IS on Tuesday, we know Iris IS on Monday. But if Nancy ISN'T on Tuesday...could Iris still be on Monday? Yep! Iris COULD be on Monday in this scenario, she also might not be. We don't know for sure because we don't have a rule that addresses what happens when Nancy ISN'T on Tuesday.
So for this question, we are given that K is in Wednesday. When you apply rule 4, that means that V is in Tuesday. We know from rule 1 that N is not in Monday, so with that, we're left with the below setup:
H/I - V- K - _ - _
We also know that one of the last two must be N.
A) Out, because if Iris is scheduled for Friday, that means only H is left to be in Monday. However, we know from rule 2 that if H is in Monday, N is in Friday...so saying I is in Friday doesn't work.
B) Out, because of rule 4 we know Tuesday is filled up by V already.
C) This looks good! To test it, you can put I in Monday, leaving you with I - V -K - _ - _. If you put N before H in the last two for a I - V- K - I -N - H scenario, it doesn't break any rules.
D) Out. If N comes before I, that means I isn't in Monday, so H must be. But if H is in Monday, according to rule 2, that means N has to be in Friday...which is the last day of the week, so N can't come before I.
E) Out, because as we know from the initial setup and rule 4, if K is in Wednesday then V must be in Tuesday. The only day left coming before K is Monday, but we know from rule 1 that N can't be in Monday, so there's no way N can come before K.
Hope this helps!
SOULCAGES71February 24, 2023
... just to make sure I am understanding this correctly:
Saying "if Nancy isn't on Tuesday, Iris can't go on Monday" is mistaken negation. That's incorrect because if Nancy isn't on Tuesday, we don't actually know what happens. The rule only addresses what happens when Nancy IS on Tuesday. If Nancy IS on Tuesday, we know Iris IS on Monday. But if Nancy ISN'T on Tuesday...could Iris still be on Monday? Yep! Iris COULD be on Monday in this scenario, she also might not be. We don't know for sure because we don't have a rule that addresses what happens when Nancy ISN'T on Tuesday.
It sounds to me like the contrapositive is really a "could be or could not be true" situation for the 1st and reversed negation, is that correct... meaning that if Iris is NOT on Monday, it REALLY means that Iris may or may not be on Monday. Is it safe to approach these contrapositives this way? I ask because they are really throwing me for a loop. Thank you
Emil-KunkinMarch 1, 2023
The contrapositive is always a must be true situation, in this case the contrapositive is that if I is not M, then N is not T. I might not be understanding your question, but it looks like you may be confusing a contrapositive (reverse and negate) with a mistaken negation. (Negate without reversing)
