Two puzzles I cant solve, want help. logic one

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abdur-rehmaan
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Joined: Fri 29 May, 2015 8:12 pm

Two puzzles I cant solve, want help. logic one

Post by abdur-rehmaan » Fri 29 May, 2015 8:35 pm

First one,

There are three trains in front of you: two steam and diesel. However, you are blindfolded, so you cannot see which one is which.

You can ask one yes-no question to any one of the three trains. If you ask the question to a steam, he will answer your question truthfully. If you ask the question to the Diesel, he will answer randomly (he could answer yes or no).

What single question can you ask to identify, with certainty, the location of one of the steams?

Second,

A group of dogs are stranded on Island, with assorted coloured furs. They are all perfect logicians - if a conclusion can be logically deduced, they will do it instantly. Each of them can see out of his own muzzle, but cannot see himself. This means each can see the colour fur of everyone else, but does not know the colour of his own fur. Every night at midnight, a ferry stops at the island, to take the dogs to safety. But, there is a catch. Dogs can only leave the island if they know what colour fur they have. Other than sight, they cannot communicate (being dogs of course). There are no mirrors, reflecting surfaces on the island, and everyone knows the rules in this paragraph.

On this island, there are 20 white coloured dogs, and 20 black coloured dogs, although the dogs do not know this. So any given white dog can see 19 white dogs and 20 black dogs, but this doesn't tell himself what colour he has. For all he knows, he could have a black paint and there are 21 black dogs in total, or he could have a red, or orange paint.

Suddenly, on one day, a booming voice calls from the sky, and shouts:

"There is a white dog on the island"

Who leaves, and on which following night?

Thanks. :D

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