Logic Riddles

Question: There are 100 prisoners lining up to go to jail. Each prisoner is wearing a hat that is either black or white. The prisoners don't know their own hat color, just the hat color of those in front of them in line (the first prisoner in line can't see anyone's hat and the last prisoner can see everyone's hat except their own). Starting from the back, one of the guards asks each prisoner what color their hat is. If they are correct they get to go free but if they are wrong they go to jail.If the prisoners get to discuss a plan, how can at least 99 of them be saved?

Question: You have found a mutant algae that doubles in size every hour. It takes 18 hours for one algae plant to take up half of a certain lake.

How long would it take for two of these plants to take up half of the same lake?

Question: A murderer is condemned to death. He has to choose between three rooms. The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven't eaten in 3 years. Which room is safest for him?

Question: A cheap man and his wife decide to go on a trip for their 10th anniversary. They go to Brazil and while touring the rain forest his wife falls off of a bridge to her death.

Shortly after her death one of the flight attendants on their flight sees a report on her death on television. She immediately calls the police and tells them the man murdered his wife.

How did she know?

Question: Every time you lose something, you always find it in the very last place you would look.

Why is this?