Category Archives: Puzzles

Supersonic bee and trains

Problem: Two trains enter a tunnel 200 miles long, traveling at 100 mph at the same time from opposite directions. As soon as they enter the tunnel a supersonic bee flying at 1000 mph starts from one train and heads toward the other one. As soon as it reaches the other one it turns around Read More →

King and Wine Bottles

king-wine-bottle

Problem: A bad king has a cellar of 1000 bottles of delightful and very expensive wine. A neighboring queen plots to kill the bad king and sends a servant to poison the wine. Fortunately (or say unfortunately) the bad king’s guards catch the servant after he has only poisoned one bottle. Alas, the guards don’t Read More →

Blind bartender’s problem

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Problem: Four glasses are placed on the corners of a square table. Some of the glasses are upright (up) and some upside-down (down). A blindfolded person is seated next to the table and is required to re-arrange the glasses so that they are all up or all down, either arrangement being acceptable, which will be Read More →

Probability of getting one rupee coin from bag

Problem: A bag contains (x) one rupee coins and (y) 50 paise coins. One coin is taken from the bag and put away. If a coin is now taken at random from the bag, what is the probability that it is a one rupee coin? Answers: Case I: Let the first coin removed be one Read More →

Probability of finding a job

Problem: A candidate is selected for interview for 3 posts.The number of candidates for the first, second and third posts are 3,4 and 2 respectively. What is the probability of getting at least one post? Solution: The probability the candidate does not get an offer from the first interview is 2/3. The probability she doesn’t Read More →

Prisoners and Hats Puzzle

hatpuzzle

Problem: Four prisoners are arrested for a crime, but the jail is full and the jailer has nowhere to put them. He eventually comes up with the solution of giving them a puzzle so if they succeed they can go free but if they fail they are executed. The jailer puts three of the men Read More →

Probability of picking 2 socks of same color

Problem: There are 6 pairs of black socks and 6 pairs of white socks.What is the probability to pick a pair of black or white socks when 2 socks are selected randomly in darkness. This question was asked in Aamaon. Solution: Ways to pick any 2 socks from 24 socks = 24C2 Ways to pick Read More →

Age of 3 children – Mathematical Puzzle

Problem: Two old friends, Jack and Bill, meet after a long time. Jack: Hey, how are you man? Bill: Not bad, got married and I have three kids now. Jack: That’s awesome. How old are they? Bill: The product of their ages is 72 and the sum of their ages is the same as your Read More →

Red and Blue Marbles Puzzle

Puzzle: You have two jars, 50 red marbles and 50 blue marbles. You need to place all the marbles into the jars such that when you blindly pick one marble out of one jar, you maximize the chances that it will be red. When picking, you’ll first randomly pick a jar, and then randomly pick Read More →

Squares on a chess board?

Chess board squares puzzle

Problem: How many squares are on a chess board? If you thought the answer is 64, think again! How about all the squares that are formed by combining smaller squares on the chess board (2×2, 3×3, 4×4 squares and so on)? A 1×1 square can be placed on the chess board in 8 horizontal and 8 Read More →

The Fox and The Duck Puzzle

duck and fox puzzle

Problem: This is the classical puzzle asked in microsoft interview A duck, pursued by a fox, escapes to the center of a perfectly circular pond. The fox cannot swim, and the duck cannot take flight from the water. The fox is four times faster than the duck. Assuming the fox and duck pursue optimum strategies, Read More →

Gold Bar Puzzle

gold bar puzzle for interview

Puzzle: You’ve got someone working for you for seven days and a gold bar to pay him. The gold bar is segmented into seven connected pieces. You must give them a piece of gold at the end of every day. What and where are the fewest number of cuts to the bar of gold that will Read More →