# Clean riddles

## Give me a drink and I die

Feed me and I live, yet give me a drink and I die.
Fire.
69.37 %

## Against the law

Why is it against the law for a man living in Delhi to be buried in Mumbai?
Because he is still living.
69.37 %

## I will follow no matter how fast you run

Each morning I appear to lie at your feet. All day I will follow no matter how fast you run, yet I nearly perish in the midday sun.
69.35 %

## Mysterious man

One winter day, there was a man standing in the middle of someone's front yard. The person stayed there for several weeks without moving and the owner of the yard didn't mind. Eventually the man left. Who was the man?
A snowman.
69.33 %

## I'm tall when I'm young

I'm tall when I'm young and I'm short when I'm old. What am I?
A candle.
69.30 %

## The end of time and space

The beginning of eternity, The end of time and space. The beginning of every end, And the end of every place.
E.
69.30 %

## Three children

Johnny‘s mother had three children. The first child was named April. The second child was named May. What was the third child‘s name?
Johny.
69.23 %

## The same birthday

What is the least number of people that need to be in a room such that there is greater than a 50% chance that at least two of the people have the same birthday?
Only 23 people need to be in the room. Our first observation in solving this problem is the following: (the probability that at least 2 people have the same birthday + the probability that nobody has the same birthday) = 1.0 What this means is that there is a 100% chance that EITHER everybody in the room has a different birthday, OR at least two people in the room have the same birthday (and these probabilities don't add up to more than 1.0 because they cover mutually exclusive situations). With some simple re-arranging of the formula, we get: the probability that at least 2 people have the same birthday = (1.0 - the probability that nobody has the same birthday) So now if we can find the probability that nobody in the room has the same birthday, we just subtract this value from 1.0 and we'll have our answer. The probability that nobody in the room has the same birthday is fairly straightforward to calculate. We can think of this as a "selection without replacement" problem, where each person "selects" a birthday at random, and we then have to figure out the probability that no two people select the same birthday. The first selection has a 365/365 chance of being different than the other birthdays (since none have been selected yet). The next selection has a 364/365 chance of being different than the 1 birthday that has been selected so far. The next selection has a 363/365 chance of being different than the 2 birthdays that have been selected so far. These probabilities are multiplied together since each is conditional on the previous. So for example, the probability that nobody in a room of 3 people have the same birthday is (365/365 * 364/365 * 363/365) =~ 0.9918 More generally, if there are n people in a room, then the probability that nobody has the same birthday is (365/365 * 364/365 * ... * (365-n+2)/365 * (365-n+1)/365) We can plug in values for n. For n=22, we get that the probability that nobody has the same birthday is 0.524, and thus the probabilty that at least two people have the same birthday is (1.0 - 0.524) = 0.476 = 47.6%. Then for n=23, we get that the probability that nobody has the same birthday is 0.493, and thus the probabilty that at least two people have the same birthday is 1.0 - 0.493) = 0.507 = 50.7%. Thus, once we get to 23 people we have reached the 50% threshold.
69.22 %

## The thunder comes before the lightning

The thunder comes before the lightning; the lightning comes before the clouds. The rain dries everything it touches. What am I?
A volcano.
69.22 %