From K.C. Cole's "The Universe and the Teacup: the mathematics of truth and beauty":
"There is an old riddle that vividly demonstrates just how noise can interfere with thinking, even when that noise is information. Imagine you are a bus driver. At the first stop of the day, nine passengers get on your bus. At the second stop, two people get off. At the third stop, four people get off, but three new people get on. What color are the bus driver's eyes?" **And Martin Gardner had his own version of this type riddle (from his volume, "Aha!"):
"You are a taxi driver. Your cab is yellow and black, and has been in use for seven years. One of its windshield wipers is broken, and the carburetor needs adjusting. The tank holds 20 gallons. but at the moment is only three-quarters full. How old is the taxi-driver?" **
** Since YOU are the bus or taxi driver in these cases, the eye color and age are the same as your own. All the other information is just noise.
(...meanwhile, LOTSA math links compiled over at MathTango this morning for your perusal.)