Jim and his wife Patty were sitting in bed together one evening while a thunderstorm raged outside. After a bolt of lightning followed by a loud clap of thunder, the lights went out. Jim stopped reading and went to sleep, but Patty continued reading in the dark. How did she do it?
Patty is blind and was reading a Braille book so she didn’t need the light to begin with. Of course this also meant she didn’t know Jim snuck downstairs to get some cookies, but we’ll just keep that quiet.
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.
There once was a strange man who loved wordplay, he had a very important and successful business that would take insect shipments from all across the world and distribute them to zoos across the US.
Your back. You have one and it’s easy to touch but hard to look it. A common phrase is to “watch your back” and it’s common to “have your friend’s back.” When apologizing, you often want to take back what you said. You can throw out your back, but you can’t throw it away. And back pain causes people pain every day.
