• Brain Teasers & Puzzles

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    • On Bagshot Island, there is an airport. The airport is the homebase of an unlimited number of identical airplanes. Each airplane has a fuel capacity to allow it to fly exactly 1/2 way around the world, along a great circle. The planes have the ability to refuel in flight without loss of speed or spillage of fuel. Though the fuel is unlimited, the island is the only source of fuel.
      What is the fewest number of aircraft necessary to get one plane all the way around the world assuming that all of the aircraft must return safely to the airport? How did you get to your answer?

      Notes:
      (a) Each airplane must depart and return to the same airport, and that is the only airport they can land and refuel on ground.
      (b) Each airplane must have enough fuel to return to airport.
      (c) The time and fuel consumption of refueling can be ignored. (so we can also assume that one airplane can refuel more than one airplanes in air at the same time.)
      (d) The amount of fuel airplanes carrying can be zero as long as the other airplane is refueling these airplanes. What is the fewest number of airplanes and number of tanks of fuel needed to accomplish this work? (we only need airplane to go around the world)

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    • You are the ruler of a medieval empire and you are about to have a celebration tomorrow. The celebration is the most important party you have ever hosted. You’ve got 1000 bottles of wine you were planning to open for the celebration, but you find out that one of them is poisoned.

      The poison exhibits no symptoms until death. Death occurs within ten to twenty hours after consuming even the minutest amount of poison.

      You have over a thousand slaves at your disposal and just under 24 hours to determine which single bottle is poisoned.

      You have a handful of prisoners about to be executed, and it would mar your celebration to have anyone else killed.

      What is the smallest number of prisoners you must have to drink from the bottles to be absolutely sure to find the poisoned bottle within 24 hours?

      king and poisioned wine puzzle

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    • The king’s only children, Abel, Benjamin and Paula, went into the forest with their friend, the elderly Sir Kay. They wanted to try their skill with their bows and arrows. Each of them started with same number of arrows.
      When all the arrows had been shot, it was discovered that:

      1. Sir Kay brought down more game than Princess Paula.
      2. Prince Benjamin captured more than Sir Kay.
      3. Princess Paula’s arrows went truer than Prince Abel’s.

      Who was the best marksman that day?

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    • Meanwhile, back at the castle, the ogre found that the
      boots he had picked at random from his dark storeroom
      were all six-league boots. He threw them back. He
      needed seven-league boots so that he could cover more
      territory.
      If in that dark storeroom he had four six-league boots
      and eight seven-league boots, how many boots did he
      have to pull out to make sure he had a pair of sevenleague
      boots?

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    • The king had his doubts about his sons’ fighting
      skills, and so he sent his two eldest to the court magidan
      for potions to help fight the ogre.
      The magician kept his magic hidden, mindful of the
      danger of his potent potion falling into the wrong
      hands. In a secret but inconvenient compartment in his
      laboratory, he hoarded:
      1. four ogre-fighters
      2. three dragon-destroyers
      3. two evil wizard-vanquishers
      How many potions did he have to reach for in order
      to make sure that he could give an ogre-fighter to each
      of the king’s two sons?

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    • To enlist the help of the other kingdoms, the king talked to the queen about inviting neighboring royalty to dinner. This put the queen into a royal snit. Theirs was not a very wealthy kingdom and the royal dinnerware was in a disgraceful condition. Apart from ordinary dishes for everyday use, all that the royal pantry contained were a few dinner plates of three different
      dinner patterns:
      1. five silver ones with birds
      2. six crystal with seashells
      3. seven gold with the royal crest
      They were all stored in disarray on a very dark top shelf of the royal pantry. Only those would be suitable for entertaining other royalty.
      If the queen didn’t want to climb up to the top shelf twice, how many dinner plates would she have to take down to be sure she had matching dinner plates for herself, her royal spouse, and for the neighbouring king and queen?

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    • The local king, determined to defend his kingdom from that wicked ogre, sent his two eldest sons to the court swordsmith.
      The swordsmith kept a supply of special ogrefighters (four daggers, three swords and two axes) locked in a chest. The two princes insisted on having the same kind of weapon.
      How many weapons did the swordsmith have to take out of the chest to be sure he could meet the demands of the princes?

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    • Planning to roam the countryside and prey upon its
      defenseless people, the ogre reached into his dark
      closet. There he had stored four six-league boots and
      eight seven-league boots. How many boots did he have
      to pull out of the closet to make sure he had a pair that
      matched?

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    • On the day before the spacecraft was to return to
      Earth, the Martians held a dinner party for the crew. In
      all there were eight at the table: Aken, Bal, Mun, Mark,
      Wora, Jones, Rider and Smith.
      a. One was a history buff.
      b. One was a whiz at math.
      c. One was very tall.
      d. One was Aken’s friend.
      e. One had yellow feathers.
      f. One was a pilot.
      g. One was a rock collector.
      h. One spoke a number of languages.
      1. The person who was Aken’s friend sat directly
      opposite Mark.
      2. Wora sat between the math whiz and Aken’s
      friend.
      3. The tall one sat opposite Wora, with Aken to her
      left.
      4. Smith, who had no real friends among the group,
      sat to the right of Mun who towered over the rest
      of the group.
      5. The one who had yellow feathers sat opposite Bal,
      between Mun and the one who spoke a number of
      languages.
      6. Jones was to the right of the rock collector and
      opposite the pilot who was next to Rider.
      Who was Aken’s friend?

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    • Four Martians from different groups, the Uti,
      Grundi, Yomi and Rafi, gathered for an intraplanetary
      conference to discuss the problem of the visiting Earthlings.
      As was appropriate for diplomatic envoys, all
      were beautifully feathered in different colors, one red,
      one green, one blue and the fourth brown. Their names
      were Aken, Bal, Mun and Wora.
      1. Before the meeting, the Uti had a pleasant breakfast
      with Mun.
      2. After debating with the Martians in the blue and
      the brown feathers, Bal and the Yomi were so angry
      that they tore a wingful of feathers out of them
      before they were stopped.
      3. Wora and the Rafi, however, agreed with the diplomat
      with brown feathers, though they disagreed
      with the red-feathered Grundi.
      Who is the blue-feathered diplomat and to what
      group does he or she belong?

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