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.
Hans made a meandering journey from Paris to Roye. On the first day, he went half of the distance. On the second day, he went one third of the remaining distance. On the third day he went three quarters of the remaining distance. The next day he traveled half of the remaining distance and was left with 5 kilometers to get to Roye. How far was the entire journey?
Day 1 – 60 km (60 km remaining)
Day 2 – 20 km (40 km remaining)
Day 3 – 30 km (10 km remaining)
Day 4 – 5 km (5 km remaining)
Day 5 – 5 km (arrives in Roye)
A wise king devised a contest to see who would receive the Princess’ hand in marriage. The Princess was put in a 50 x 50 foot carpeted room. Each of her four suitors were put in one corner of the room with a small box to stand on. The first one to touch the Princess’ hand would be the winner and become the new King.
The rules were the contestants could not walk over the carpet, cross the plane of the carpet, or hang from anything; nor could they use anything but their body and wits (i.e. no magic, telepathy, nor any items such as ladders, block and tackles etc). One suitor figured out a way and married the Princess and became the new King. What did he do?
A tailor can make a pair of pants from the scraps left over from sewing up five pairs of pants. If he has twenty-five scraps, how many pairs of pants can he make?
Six pairs of pants. He can make five initially, but once he’s done making five pairs of pants, he’ll have five remaining sets of scraps, meaning he can make an additional pair of pants, totaling six.
Someone bowled a strike. The ten white men are the pins, the dirt road is the bowling alley (it’s not dirt, but it’s the color of dirt, and if it said a smooth wooden alley it wouldn’t be much of a riddle). Three eyes as black as night are the finger holes in the bowling ball.
You’re waiting to board your flight at the airport with 99 other passengers, each with an assigned seat. All but one of the passengers will gladly sit in their designated seat. The only exception is Randall, a scoundrel who refuses to follow the rules. When he boards, he will choose a random, unoccupied seat.
If a rule-following passenger finds someone in their spot, they will choose another one at a random from the remaining unoccupied seats.
What is the probability that the last person to board the plane will sit in their proper seat?
The randomness stops as soon as someone else sits in Randall’s assigned seat. The chances of this happening range from 1 out of 99 to 1 out of 1 (when only one seat remains).
Thus, the probability of the last person sitting in their own seat can be calculated as 1/99 plus the sum of 2 to 98 of the formula 1 / n × (n + 1), which works out to 0.5, or 50%.
So there’s a 50% chance the last passenger will sit in their own seat thanks to Randall for screwing up order and procedure when boarding an aircraft.
My first wears my second; my third might be
What my first would acquire if he went to the sea.
Put together my one, two, three
And the belle of New York is the girl for me.
Mary was out riding a frisky pony in a meadow by the sea when the bridle came loose. The animal shook it off and started to gallop full speed toward the ocean, paying no attention to Mary’s yelling to slow down. She couldn’t bear to jump off and lose her beloved pony, so she stayed on and hoped for the best. When the cliff loomed ahead of her, she knew she had to stop the pony. How did she do it?
