SuperPrep B Logic Game #2 Question 10

mistd
Posts: 27
Joined: Tue May 21, 2013 11:52 am

SuperPrep B Logic Game #2 Question 10

Postby mistd » Mon Jun 03, 2013 7:34 pm

I don't understand the relationship between firs and maple.

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CardozoLaw09
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Joined: Sat Aug 28, 2010 1:58 pm

Re: SuperPrep B Logic Game #2 Question 10

Postby CardozoLaw09 » Mon Jun 03, 2013 7:47 pm

1.Maples --> ~Yews
2. Firs --> ~Pines
3.~Yews --> L or O (not both)
4.~(L+O) --> F +S

Combine 1. and 3. to yield: Maples -->~Yews--->L or O (not both)

10. If Firs are not in the park then from the contrapositive of 4. we know that both L and O must be in the park. If both L and O must be in the park then maples can't be in the park because that would require, from the combined conditional statements of 1. and 3. to have either L or O in the park. So by deduction Maples cannot be in the park.

mistd
Posts: 27
Joined: Tue May 21, 2013 11:52 am

Re: SuperPrep B Logic Game #2 Question 10

Postby mistd » Mon Jun 03, 2013 8:00 pm

CardozoLaw09 wrote:1.Maples --> ~Yews
2. Firs --> ~Pines
3.~Yews --> L or O (not both)
4.~(L+O) --> F +S

Combine 1. and 3. to yield: Maples -->~Yews--->L or O (not both)

10. If Firs are not in the park then from the contrapositive of 4. we know that both L and O must be in the park. If both L and O must be in the park then maples can't be in the park because that would require, from the combined conditional statements of 1. and 3. to have either L or O in the park. So by deduction Maples cannot be in the park.


But how do we know that both L & O are in the park from the contrapositive of 4?
I thought the contrapositive of 4 was:

~F or ~S --> L or O

Thank you!




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