Math Riddles

Question: A claustrophobic person gets on a train. The train enters a tunnel just as it is leaving the station.

Where is the best place for him to sit?

Question: John has been hired to paint the numbers 1 through 100 on 100 apartments.

How many times with he have to paint 8?

Question: Two men find an old gold coin and want to have a coin toss with it to decide who gets it. The only problem is the coin is heavier on one side so it comes up heads more than tails. What is a fair way for the men to toss the coin and decide who gets the coin?

Question: What are the next two letters in the following series and why? WATNTLITFS__

Question: A man wants to have a party in thirty-one days where he will be serving his 1000 barrels of wine. The only problem is that one of his enemies poisoned one of the barrels. The poison kills any man who drinks any of the wine in about 30 days, give or take a few hours. The man has 10 plants that are also killed by the poison in 30 days and can be used to test the wine. How can identify the single poisoned barrel of wine?