You are a bus driver. The bus starts out empty. At the first stop 4 people get on. At the second stop, 8 people get on and 3 get off. At the third stop, 2 people get off and 4 get on. The question is, what color are the bus driver's eyes?
A plane crashes directly on the border between Canada and USA, where are the survivors buried?
This was from my graduate student days almost two decades ago:
You are given several pieces of ropes (more than you need to solve the problem). Each rope has the identical characteristic that if you light it up with fire on one end, it would take precisely 4 minutes to finish burning (burned to the other end).
However, the burning process is highly nonlinear and not the same for each rope -- for example, rope A of 3 feet in length may take 3:58 just to consume the first inch, then 0:02 to finish the remaining two feet and 11 inches, where as rope B of 10 feet in length may take 1:00 to burn up the first 9 feet, and the remaining 3:00 to finish the remaining 1 foot. Anyway, the only known fact you can rely on is that it takes 4 minutes to burn up each rope, each with a different and unknown underlying process.
Now, make a 7-minute timer using these ropes and a lighter.
The 7-minute must be achieved continuously, and in real time. In other words, once the 7-minute is up, you must be able to declare it immediately.
Here's a couple good ones for kids:
You are a bus driver. The bus starts out empty. At the first stop 4 people get on. At the second stop, 8 people get on and 3 get off. At the third stop, 2 people get off and 4 get on. The question is, what color are the bus driver's eyes?
A plane crashes directly on the border between Canada and USA, where are the survivors buried?
Thank you. My faith in BBI has been restored.
Friday is the name of his horse?
Q: On what side of the school does the elm tree always grow?
A couple of my favorites.
LOL … love it!
The problem is to fill one of the jugs with exactly 4 gallons of water. How do you do it?
Quote:
A cowboy rides into town of Friday. Stays 3 days and then leaves on Friday. How did he do it?
Friday is the name of his horse?
Either that, or Friday is the name of the town ("town of Friday," though that might have been a typo), and he arrived on Tuesday.
Now you empty the 3er and pour the 2 from the 5er into it.
Now you fill the 5er and top off the remaining 1 in the 3er.
5-1=4.
You are given several pieces of ropes (more than you need to solve the problem). Each rope has the identical characteristic that if you light it up with fire on one end, it would take precisely 4 minutes to finish burning (burned to the other end).
However, the burning process is highly nonlinear and not the same for each rope -- for example, rope A of 3 feet in length may take 3:58 just to consume the first inch, then 0:02 to finish the remaining two feet and 11 inches, where as rope B of 10 feet in length may take 1:00 to burn up the first 9 feet, and the remaining 3:00 to finish the remaining 1 foot. Anyway, the only known fact you can rely on is that it takes 4 minutes to burn up each rope, each with a different and unknown underlying process.
Now, make a 7-minute timer using these ropes and a lighter.
The 7-minute must be achieved continuously, and in real time. In other words, once the 7-minute is up, you must be able to declare it immediately.
The outside?