Three cars had driven into a parking lot at the same time, and the three drivers left them all for the attendant to park. Unfortunately, he isn't too good at remembering exactly which driver drove which car. However, he is sure of these 6 facts: a. Colin drove the BMW if and only if Mr. Cooper drove the Avenger. b. Alan drove the Cortina if and only if Mr. Cooper drove the BMW. c. Colin is Mr. Brown if and only if Mr. Andrews drove the BMW. d. Brian is Mr. Andrews if and only if Colin drove the BMW. e. Mr. Cooper drove the Avenger if and only if Alan is Mr. Brown. f. Colin is Mr. Brown if and only if Alan drove the Cortina. Who arrived with which car?
Brian Brown drove the BMW, Alan Andrew drove the Avenger, and Colin Cooper drove the Cortina.
I have 10 red socks and 10 blue socks in a drawer. How many socks must I take out to ensure that I have at least one matching pair? One how many to ensure I have at least a pair of red and a pair of blue?
Three for one pair, and twelve to ensure one pair of each color.
An old parchment describes the location of buried treasure: "On the island there are only two trees, A and B, and the remains of a gallows. Start at the gallows and count the steps required to walk in a straight line to tree A. At the tree turn 90 degrees to the left and then walk forward the same number of steps. At the point where you top drive a spike into the ground. Now return to the gallows and walk in a straight line, counting your steps, to tree B. When you reach the tree, turn 90 degrees to the right and take the same number of steps forward, placing another spike at the point where you stop. Dig at the point exactly halfway between the spikes and you will find the treasure." However, our hero when he gets to the island finds the gallows missing. Is there any way he can still get to the treasure?
A simple experiment with a ruler and paper shows that any position for the gallows leads to the same point.
A hiker comes to a fork in the road and doesn't know which way to go to reach his destination. There are two men at the fork, one of whom always tells the truth while the other always lies. The hiker doesn't know which is which, though. He may ask one of the men only one question to find his way. Which man does he ask, and what is the question?
Either man should be asked the following question: "If I were to ask you if this is the way I should go, would you say yes?" While asking the question, the hiker should be pointing at either of the directions going from the fork.