Question: Four people need to cross a bridge in 17 minutes in the middle of the night. The bridge can only hold two or less people at any time and they only have one flashlight so they must travel together (or alone). The flashlight can only travel with a person so every time it crosses the bridge it must be carried back. Tom can cross in 1 minute, John can cross in 2 minutes, Sally can cross in 5 minutes, and Connor can cross in 10 minutes. If two people cross together they go as fast as the slower person.How can they cross the bridge in 17 minutes or less?
Answer: First Tom and John will cross (2 minutes). Then Tom will bring the flashlight back (1 minute). Next Sally and Connor will cross (10 minutes). Then John will bring the flashlight back (2 minutes). Finally John and Tom will cross (2 minutes). 2 + 1 + 10 + 2 + 2 = 17 minutes.
Question: You come to a cross road and see a man with two heads. A sign tells you that one head always tells the truth and the other one always lies. The sign also tells you that one road leads to life and posterity while the other leads to certain death. Now the hard part. You can only ask ONE head ONE question. What do you ask? Which road do you take? Hint: One head knows what the other will tell you.
Answer: You ask, "Which road would the other head say." You then take the opposite road. Explanation. If you happened to ask the truth teller he would tell you that the liar would say the wrong road. Therefore you would take the opposite road. If you happened to ask the liar which one the truth teller would say he would lie and say the wrong road. You then would take the opposite road.