Why are manhole covers round? Do manhole covers really need to be circular?
Manhole covers are round so that they won't fall through the hole into the sewer below them. No matter how you turn the cover, you won't be able to push the cover through the hole.
However, if you were to have square manhole covers, you would be able to rotate the cover such that one of the edges of the square cover is lined up with the diagonal line of the square hole, which would allow the cover to fall through, causing countless problems that the general public would rather avoid.
There are several chickens and rabbits in a cage (with no other types of animals). There are 72 heads and 200 feet inside the cage. How many chickens are there, and how many rabbits?
There are 44 chickens and 28 rabbits in the cage.
Let c be the number of chickens, and r be the number of rabbits.
r + c = 72
4r + 2c = 200
To solve the equations, we multiply the first by two, then subtract the second.
2r + 2c = 144
2r = 56
r = 28
c = 44
In medieval England, a king's jester was imprisoned (the king didn't like the jester's jokes). The jester was locked in a room at the top of a high tower. The room had only one tiny window. The jester found a piece of rope. It wasn't long enough to reach the ground. So, he divided it in half and tied the two halves together. This made the rope long enough and he escaped. How?
Bill and Stacie are delighted when their new baby, Patrick, is born on February 29th, 2008. They think it's good luck to for him to be born on the special day of the leap year. But then they start thinking about when to celebrate his next birthday. After some thought, they decide that they want to celebrate Patrick's next birthday (when he turns 1) exactly 365 days after he was born, just like most people do.
What will be the date of this birthday?
The date of the birthday will be February 28th, 2009.
At first it might seem like his birthday should be March 1st, 2009, since February 29th is the day after February 28th in the leap year, while March 1st is the day after February 28th in non-leap years. But this is the wrong way to think about it.
The right way to think about it is that 365 days after the day before March 1st is always February 28th, regardless of whether it's a leap year or not. So Patrick's birthday will be February 28th.
What 8 letter word can have a letter taken away and it still makes a word. Take another letter away and it still makes a word. Keep on doing that until you have one letter left. What is the word?
The word is starting! starting, staring, string, sting, sing, sin, in, i.
Alexander is stranded on an island covered in forest.
One day, when the wind is blowing from the west, lightning strikes the west end of the island and sets fire to the forest. The fire is very violent, burning everything in its path, and without intervention the fire will burn the whole island, killing the man in the process.
There are cliffs around the island, so he cannot jump off. How can the Alexander survive the fire? (There are no buckets or any other means to put out the fire)
Alexander picks up a piece of wood and lights it from the fire on the west end of the island. He then quickly carries it near the east end of he island and starts a new fire. The wind will cause that fire to burn out the eastern end and he can then shelter in the burnt area. Alexander survives the fire, but dies of starvation, with all the food in the forest burnt.
