# Another Game -- Exam 33, sec 4, #7 (forest)

#### nemo

##### Another Game -- Exam 33, sec 4, #7 (forest)
« on: September 08, 2005, 07:06:46 PM »
I'm having some trouble setting this one up. Your help is much appreciated!

Bird-watchers explore a forest to see which of the following six kinds of birds -- grosbeak, harrier, jay, martin, shrike, wren -- it contains. The findings are consistent with the following conditions:

If harriers are in the forest, then grosbeaks are not.
If jays, martins, or both are in the forest, then so are harriers.
If wrens are in the forest, then so are grosbeaks.
If jays are not in the forest, then shrikes are.

7. If both martins and harriers are in the forest, then which one of the following must be true?
a) Shrikes are the only other birds in the forest
b) jays are the only other birds in the forest
c) the forest contains neither jays nor shrikes
d) there are at least two other kinds of birdes in the forest
e) there are at most two other kinds of birds in the forest

#### kmanista

##### Re: Another Game -- Exam 33, sec 4, #7 (forest)
« Reply #1 on: September 08, 2005, 07:16:49 PM »
Sorry hon, I can't help you with the rest of these tonight.  I'll write out my thinking on them in the morning if no one else has helped you out.

#### nemo

##### Re: Another Game -- Exam 33, sec 4, #7 (forest)
« Reply #2 on: September 08, 2005, 07:36:31 PM »
Thank you for your time Alixana.

#### dolphin

##### Re: Another Game -- Exam 33, sec 4, #7 (forest)
« Reply #3 on: September 08, 2005, 07:46:10 PM »
This is formal logic game.

You have:
h -> no g
j|m -> h
w -> g
no j -> s  ... s -> no j (contra)

Therefore if you have m and h, you can't have g (h -> no g) and there for no w (w -> g). Of the 6 types of birds (ghjmsw), now you only have j and s left. They are not mutually exclusive so answer E: there are at most two other kinds of birds in the forest should be correct.