Brainteaser: Which word in the dictionary is always spelled incorrectly?
Brainteaser: How is seven different from the rest of the numbers between one and 10?
Answer: Seven is the only one with two syllables.
Brainteaser: Four people come to a river at night. There is a narrow bridge, and they have only one flashlight. The bridge can only hold two people at a time, and the group must cross it in the shortest possible time. Each person walks at a different speed: one can cross the bridge in 1 minute, another in 2 minutes, the third in 5 minutes, and the slowest in 10 minutes. When two people cross the bridge together, they must go at the slower person’s pace. What’s the shortest time for all four to cross the bridge?
The sequence of crossings goes as follows:
The 1-minute and 2-minute people cross together (2 minutes).
The 1-minute person goes back (1 minute).
The 5-minute and 10-minute people cross together (10 minutes).
The 2-minute person goes back (2 minutes).
The 1-minute and 2-minute people cross together again (2 minutes).
Total time: 2 + 1 + 10 + 2 + 2 = 17 minutes.
Brainteaser: You have two coins: one is fair (50% chance of heads, 50% chance of tails), and the other is double-headed (100% chance of heads). You randomly pick one coin and flip it. It comes up heads. What is the probability that you picked the fair coin?
Answer: The probability is 1/3 that you picked the fair coin and 2/3 that you picked the double-headed coin.
Brainteaser: You’re on a game show, and there are three doors. Behind one door is a car, and behind the other two doors are goats. You pick a door, then the host, who knows what’s behind each door, opens another door to reveal a goat. You’re given the option to switch your choice to the remaining unopened door. What should you do to maximize your chance of winning the car?
Answer: You should switch doors. By switching, your chance of winning becomes 2/3, whereas if you stick with your initial choice, your chance remains 1/3.