A lemon. It’s a citrus fruit whose juice is acidic and can be used to conduct electricity for motors. A car or other purchase that has problems is known as a lemon and can be expensive to repair. Lemons have a tart flavor but do little harm (unless you get it in a cut, then it hurts like the dickens). The old saying goes, “When life gives you lemons, make lemonade” (I know, it’s spelled aid not ade but it sounds the same and wouldn’t make any sense the other way. It all works out nicely when the riddle is told instead of read.)
A train is a half mile long and is about to enter a 10 mile tunnel. If the train is traveling at 35mph, how long will it take for the entire train to make it through the tunnel, from the front of the train entering to the end of the train leaving the tunnel?
Four cards are placed in front of you on the table, each with a number on one side and a color on the other. The visible cards show 3, 8, red and brown. Which cards should you turn over in order to test the truth of the statement that if a card shows an even number on one face, then its opposite face is red?
You’d need to turn over only the 8 and brown card. Only a card with an even number on one face and which is not red on the other face can invalidate the stated rule. If you turn over the 3 card and it’s not red, it doesn’t invalidate the rule, nor does turning over the red card and finding it has the label 3.
This test was devised by Peter Cathcart Wason and is known as the Wason selection task. Less than 10% of test subjects got it correct in two separate studies.
