Logic riddles

logicmathcleancleversimple

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?
You will never reach the door! If you only move half the distance, then you will always have half the distance remaining no matter, how small is the number.
71.67 %
88 votes
logicsimplecleverinterviewstory

Betty signals to the headwaiter in a restaurant, and says, "There is a fly in my tea." The waiter says "No problem Madam. I will bring you a fresh cup of tea." A few minutes later Betty shouts, "Get me the manager! This is the same cup of tea." How did she know? Hint: The tea is still hot.
Betty had already put sugar in her tea before sending it back. When the "new" cup came, it was already tasted sweet.
71.67 %
88 votes
logicsimpleclean

Jay escaped from jail and headed to the country. While walking along a rural road, he saw a police car speeding towards him. Jay ran toward it for a short time and then fled into the woods. Why did he run toward the car?
Jay was just starting to cross a bridge when he saw a police car. He ran toward the car to get off the bridge before running into the woods.
71.64 %
63 votes
logiccleanclevermath

At a dinner party, many of the guests exchange greetings by shaking hands with each other while they wait for the host to finish cooking. After all this handshaking, the host, who didn't take part in or see any of the handshaking, gets everybody's attention and says: "I know for a fact that at least two people at this party shook the same number of other people's hands." How could the host know this? Note that nobody shakes his or her own hand.
Assume there are N people at the party. Note that the least number of people that someone could shake hands with is 0, and the most someone could shake hands with is N-1 (which would mean that they shook hands with every other person). Now, if everyone at the party really were to have shaken hands with a different number of people, then that means somone must have shaken hands with 0 people, someone must have shaken hands with 1 person, and so on, all the way up to someone who must have shaken hands with N-1 people. This is the only possible scenario, since there are N people at the party and N different numbers of possible people to shake hands with (all the numbers between 0 and N-1 inclusive). But this situation isn't possible, because there can't be both a person who shook hands with 0 people (call him Person 0) and a person who shook hands with N-1 people (call him Person N-1). This is because Person 0 shook hands with nobody (and thus didn't shake hands with Person N-1), but Person N-1 shook hands with everybody (and thus did shake hands with Person 0). This is clearly a contradiction, and thus two of the people at the party must have shaken hands with the same number of people. Pretend there were only 2 guests at the party. Then try 3, and 4, and so on. This should help you think about the problem. Search: Pigeonhole principle
71.64 %
63 votes
interviewlogicsimple

One day a scholar came to the court of Emperor Akbar and challenged Birbal to answer his questions and thus prove that he was as clever as people said he was. He asked Birbal: "Would you prefer to answer a hundred easy questions or just a single difficult one?" Both the emperor and Birbal had had a difficult day and were impatient to leave. "Ask me one difficult question," said Birbal. "Well, then tell me," said the man, "which came first into the world, the chicken or the egg?" "The chicken," replied Birbal, very confidently. "How do you know?" asked the scholar, a note of triumph in his voice. What did Birbal answer to this?
Birbal told the scholar, "We had agreed you would ask only one question and you have already asked it" and he and the emperor walked away leaving the scholar gaping.
71.62 %
96 votes
logic

There are 4 big houses in my home town. They are made from these materials: red marbles, green marbles, white marbles and blue marbles. Mrs Jennifer's house is somewhere to the left of the green marbles one and the third one along is white marbles. Mrs Sharon owns a red marbles house and Mr Cruz does not live at either end, but lives somewhere to the right of the blue marbles house. Mr Danny lives in the fourth house, while the first house is not made from red marbles. Who lives where, and what is their house made from ?
From, left to right: #1 Mrs Jennifer - blue marbles #2 Mrs Sharon - red marbles #3 Mr Cruz - white marbles #4 Mr Danny - green marbles If we separate and label the clues, and label the houses #1, #2, #3, #4 from left to right we can see that: a. Mrs Jennifer's house is somewhere to the left of the green marbles one. b. The third one along is white marbles. c. Mrs Sharon owns a red marbles house d. Mr Cruz does not live at either end. e. Mr Cruz lives somewhere to the right of the blue marbles house. f. Mr Danny lives in the fourth house g. The first house is not made from red marbles. By (g) #1 isn't made from red marbles, and by (b) nor is #3. By (f) Mr Danny lives in #4 therefore by (c) #2 must be red marbles, and Mrs Sharon lives there. Therefore by (d) Mr Cruz must live in #3, which, by (b) is the white marbles house. By (a) #4 must be green marbles (otherwise Mrs Jennifer couldn't be to its left) and by (f) Mr Danny lives there. Which leaves Mrs Jennifer, living in #1, the blue marbles house.
71.61 %
100 votes
cleanstorylogicclever

After recent events, Question Mark is annoyed with his brother, Skid Mark. Skid thought it would be funny to hide Question's wallet. He told Question that he would get it back if he finds it. So, first off, Skid laid five colored keys in a row. One of them is a key to a room where Skid is hiding Question's wallet. Using the clues, can you determine the order of the keys and which is the right key? Red: This key is somewhere to the left of the key to the door. Blue: This key is not at one of the ends. Green: This key is three spaces away from the key to the door (2 between). Yellow: This key is next to the key to the door. Orange: This key is in the middle.
The order (from left to right) is Green, Red, Orange, Blue, Yellow. The blue key is the key to the door.
71.59 %
108 votes
logicsimplestory

A number of people have broken the sound barrier, either in a super-fast car, or in nice fancy planes. However, hundreds of years ago it was broken on horseback. How?
Many people who ride horses carry whips. They crack the whip while they ride the horse. When a whip is cracked, the tip travels faster than the speed of sound, which makes the loud snap. It actually creates a miniature sonic boom of sorts. The whip breaks the sound barrier, thus, it was broken on horseback.
71.56 %
67 votes