Best difficult riddles


In a supermarket, the first 25 customers of the day purchased an average of two items each. After a further 15 customers, the average number of items purchased by each customer rose to eight. What was the average number of items purchased by the last 15 customers only?
((15+25) x 8 - (25 x 2))/15 = 18
62.91 %
47 votes

A rich man's son was kidnapped. The ransom note told him to bring a valuable diamond to a phone booth in the middle of a public park. Plainclothes police officers surrounded the park, intending to follow the criminal or his messenger. The rich man arrived at the phone booth and followed instructions but the police were powerless to prevent the diamond from leaving the park and reaching the crafty villain. What did he do?
This is a true story from Taiwan. When the rich man reached the phone booth he found a carrier pigeon in a cage. It had a message attached telling the man to put the diamond in a small bag which was around the pigeon's neck and to release the bird. When the man did this the police were powerless to follow the bird as it returned across the city to its owner.
62.88 %
255 votes

1 11 21 1211 111221 312211 What is the next number in the sequence?
The next number it: 13112221. Each number describes the previous number. Starting with 1, the second line describes it 11 (one 1). Then the third line describes 11 as 21 (two 1's). Then the fourth line describes 21 as 1211 (one 2, one 1). This is the pattern.
62.59 %
178 votes

A witch owns a field containing many gold mines. She hires one man at a time to mine this gold for her. She promises 10% of what a man mines in a day, and he gives her the rest. Because she is blind, she has three magic bags who can talk. They report how much gold they held each day, and this is how she finds out if men are cheating her. Upon getting the job, each man agrees that if he isn't honest, then he will be turned into stone. So around the witch's mines, many statues lay! Now comes an honest man named Garry. He accepts the job gladly. The witch, who didn't trust him said, "If I wrongly accuse you of cheating me, then I'll be turned into stone." That night, Garry, having honestly done his first day's job, overheard the bags talking to the witch. He then formulated a plan... The next night, he submitted his gold, and kept 1.6 pounds of gold. Later, the witch talked with her bags. The first bag said it held 16 pounds that day. The second one said it held 5 pounds. The third one said it held 2 pounds. Beaming, the witch confronted Garry. "You scoundrel, you think you could fool me. Now you shall turn into stone!" the witch cried. One second later, the witch was hard as a rock, and very grey-looking. How did Garry brilliantly deceive the witch?
Garry put 2 lbs. in bag #1. 3 lbs. were put in bag #2. 11 lb. were put into bag #3. He then put bag #2 into bag #3, and bag #1 into bag #2. The bags only felt the weight of the gold above it. Thus they inadvertently gave the message that 23 lbs. were taken.
62.32 %
168 votes

You and a friend are standing in front of two houses. In each house lives a family with two children. "The family on the left has a boy who loves history, but their other child prefers math," your friend tells you. "The family on the right has a 7-year old boy, and they just had a new baby," he explains. "Does either family have a girl?" you ask. "I'm not sure," your friend says. "But pick the family that you think is more likely to have a girl. If they do have a girl, I'll give you $100." Which family should you pick, or does it not matter?
You should pick the house on the left. Specifically, there is a 2/3 chance that the family on the left has a girl, whereas there's only a 1/2 chance that the house on the right has a girl. This is a very counterintuitive riddle. It seems like there should always be a 1/2 chance that a given child is a girl. And in fact there is. The key word there is "given". Because we are not asking about a "given" child for the house on the left. We are asking about what could be either child. Whereas for the house on the right, we are asking about a "given" child...specifically, we're asking about the younger child. There are 3 possibilities for the children in the first house: Younger Older Girl Boy Boy Girl Boy Boy There is no "Girl, Girl" option because we know the house on the left has at least one boy. Since each of these 3 options is equally likely, and 2 of them have one girl, there is a 2/3 chance of there being a girl in the house on the left. For the house on the right, because we already know the older child is a boy, there are only two possibilities: Younger Older Girl Boy Boy Boy And as we can see, there is a 1/2 chance for the house on the right having a girl. Search for: Boy or Girl paradox
61.91 %
67 votes
logicwhat am I

Alone I am 24th, with a friend I am 20. Another friend and I am unclean. What am I?
The letter 'X'. It is the 24th letter of the alphabet, XX in Roman numerals is 20, and XXX is a label for movies that are very inappropriate (unclean).
61.55 %
187 votes

There were two women, standing and facing the opposite ways. The first lady was facing south and the second lady was facing north. But, they could see each other. How is that possible?
They were holding the mirror.
61.05 %
387 votes

An intelligent trader travels from one place to another with 3 sacks having 30 coconuts each. No sack can hold more than 30 coconuts. On the way, he passes 30 check points. At each check point, he has to give one coconut for every sack he is carrying. What is the maximum number of coconuts that he can have with him at the end of his journey?
He will have 25 coconuts with him at the end. The trick is to reduce the number of sacks as you pass checkpoints. The first 10 checkpoints require 3 coconuts each, which empties his first sack. The next 15 checkpoints require 2 coconuts each, which will empty his second stack. Now, he is left with 1 sack and 5 more checkpoints. So, the 5 checkpoints will take 1 coconut each. Therefore, he will be left with 25 coconuts.
60.54 %
296 votes