1. The Camels Four tasmanian camels traveling on a very narrow ledge encounter four tasmanian camels coming the other way. As everyone knows, tasmanian camels never go backwards, especially when on a precarious ledge. The camels will climb over each other, but only if there is a camel sized space on the other side. The camels didn't see each other until there was only exactly one camel's width between the two groups. How can all camels pass, allowing both groups to go on their way, without any camel reversing? Try solving the four Tasmanian camels problem: Tasmanian Camels Puzzle Drag a camel into the empty space. A camel may move forward one space, or jump forward over exactly one camel. Start: L L L L _ R R R R Reset Show Hint Show Solution | Comments (17) | Votes (1) Hint: Try solving the three Tasmanian camels problem first: Solution: Tasmanian Camels Solution Four camels on each side swap places. Camels only move forward. Start: L L L L _ R R R R Click Next to begin. Previous Next Play Reset
2. The Waiter Three men in a cafe order a meal the total cost of which is $15. They each contribute $5. The waiter takes the money to the chef who recognizes the three as friends and asks the waiter to return $5 to the men. The waiter is not only poor at mathematics but dishonest and instead of going to the trouble of splitting the $5 between the three he simply gives them $1 each and pockets the remaining $2 for himself. Now, each of the men effectively paid $4, the total paid is therefore $12. Add the $2 in the waiters pocket and this comes to $14.....where has the other $1 gone from the original $15? Show Solution | Comments (14) | Be the first to vote Solution: The payments should equal the receipts. It does not make sense to add what was paid by the men ($12) to what was received from that payment by the waiter ($2) Although the initial bill was $15 dollars, one of the five dollar notes gets changed into five ones. The total the three men ultimately paid is $12, as they get three ones back. So from the $12 the men paid, the owner receives $10 and the waiter receives the $2 difference. $15 - $3 = $10 + $2.
3. The Boxes There are three boxes. One is labeled "APPLES" another is labeled "ORANGES". The last one is labeled "APPLES AND ORANGES". You know that each is labeled incorrectly. You may ask me to pick one fruit from one box which you choose. How can you label the boxes correctly? Show Solution | Comments (20) | Be the first to vote Solution: Pick from the one labeled "Apples & Oranges". This box must contain either only apples or only oranges. E.g. if you find an Orange, label the box Orange, then change the Oranges box to Apples, and the Apples box to "Apples & Oranges."
4. The Cannibals Three cannibals and three anthropologists have to cross a river. The boat they have is only big enough for two people. The cannibals will do as requested, even if they are on the other side of the river, with one exception. If at any point in time there are more cannibals on one side of the river than anthropologists, the cannibals will eat them. What plan can the anthropologists use for crossing the river so they don't get eaten? Note: One anthropologist can not control two cannibals on land, nor can one anthropologist on land control two cannibals on the boat if they are all on the same side of the river. This means an anthropologist will not survive being rowed across the river by a cannibal if there is one cannibal on the other side. Show Solution | Comments (18) | Be the first to vote Solution: First, two cannibals go across to the other side of the river, then the rower gets called back. Next, the rowing cannibal takes the second across and then gets called back, so now there are two cannibals on the far side. Two anthropologists go over, then one anthropologist accompanies one cannibal back, so now there is one anthropologist and one cannibal on the far side. The last two anthropologists go over to the far side, so now all the anthropologists are across the other side, along with the boat and one cannibal. In two trips, the cannibal on the far side takes the boat and ferries the other two cannibals across the river.
5. The Father A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child. Where's the father? Show Solution | Comments (28) | Be the first to vote Solution: With the mother. If you do the math, you find out the child will be born in 9 months.
6. The Double Jeopardy Doors You are trapped in a room with two doors. One leads to certain death and the other leads to freedom. You don't know which is which. There are two robots guarding the doors. They will let you choose one door but upon doing so you must go through it. You can, however, ask one robot one question. The problem is one robot always tells the truth ,the other always lies and you don't know which is which. What is the question you ask? Show Hint Show Solution | Comments (13) | Be the first to vote Hint: The two robots know each others personality. That they talk when they're bored, lonely, etc. Try to get the two robots to cancel their evil & good ways out. Solution: Ask one robot what the other robot would say, if it was asked which door was safe. Then go through the other door.
7. The Frog A frog is at the bottom of a 30 meter well. Each day he summons enough energy for one 3 meter leap up the well. Exhausted, he then hangs there for the rest of the day. At night, while he is asleep, he slips 2 meters backwards. How many days does it take him to escape from the well? Note: Assume after the first leap that his hind legs are exactly three meters up the well. His hind legs must clear the well for him to escape. Guess: Guess | Show Hint Show Solution | Comments (11) | Be the first to vote Hint: Try to think the problem through for a five meter well. Now what is the solution for the 30 meter well? Solution: 28 Each day he makes it up another meter, and then on the twenty eighth day he can leap three meters and climb out.
8. The Bobber You can paddle your canoe seven miles per hour through any placid lake. The stream flows at three miles per hour. The moment you start to paddle up stream a fisherman looses one of his bobbers in the water fourteen miles up stream of you. How many hours does it take for you and the bobber to meet? Guess: Guess | Show Hint Show Solution | Comments (40) | Be the first to vote Hint: Assume the stream moves at a perfectly constant three miles an hour. Solution: 2 Ignore the speed of the stream, as the cork will be carried along at three miles per hour as will you. It takes two hours to travel fourteen miles, at a rate of seven miles per hour.
9. The Socks Cathy has twelve black socks and twelve white socks in her drawer. In complete darkness, and without looking, how many socks must she take from the drawer in order to be sure to get a pair that match? Guess: Guess | Show Hint Show Solution | Comments (9) | Be the first to vote Hint: Assume these socks are the exact same other than the color. Solution: 3 Socks do not come in in left and right, so any black will pair with any other black and any white will pair with any other white. If you have three socks and they are either colored black or white, then you will have at least two socks of the same color, giving you one matching pair.
10. There is something about Mary Mary's mum has four children. The first child is called April. The second May. The third June. What is the name of the fourth child? Show Solution | Comments (8) | Be the first to vote Solution: Mary. Mary's mothers fourth child was Mary herself.
11. Petals Around the Rose The name of the game is Petals Around the Rose, and that name is significant. Newcomers to the game can be told that much. They can also be told that every answer is zero or an even number. They can also be told the answer for every throw of the dice that are used in the game. And that's all the information they get. The person who has the dice and knows the game, rolls five dice and remarks almost instantly on the answer. For example: in Roll #1 the answer is two. Roll #1. "The answer is what?" says the new player. "Two." "On that roll?" "Yes." "Would it still be two if I moved the dice without turning any of them over, just rearranging the pattern?" "I can tell you only three things: the name of the game, the fact that the answer is always even, and the answer for any particular throw. In this case the answer is two." "So that's how it is. What am I supposed to do?" "You're supposed to tell me the answer before I tell you. I'll give you all the time you want, but don't tell me your theory, just the answer. If you figure it out, you don't want to give the idea away to these other jokers around you. Make them work for the answers, too. If you get the answer right on six successive rolls, I'll take that as prima facie evidence that you understand the game." "OK, roll again." Roll #2. "I give up. What's the answer?" "The answer is eight." "Roll again." Roll #3. The answer is fourteen. Roll #4. The answer is zero. Roll #5. The answer is four. Roll #6. The answer is... Guess | Show Hint Show Solution | Comments (63) | Be the first to vote Hint: A claim that often accompanies these instructions is that the smarter an individual, the greater amount of difficulty the individual will have in solving it. If such a statement is true, it may be attributed to the fact that "smarter" people tend to be more knowledgeable in a wide range of information which they may unnecessarily attempt to draw upon to solve the puzzle. Solution: An integral part of the puzzle is that those who have solved it are urged to keep the solution a secret, so there is no solution posted here. It is not a hard puzzle to figure out however.
12. Watson's Selection You are shown a set of four cards placed on a table, each of which has a number on one side and a colored patch on the other side. The visible faces of the cards show 3, 8, red and brown. Which card(s) must you turn over in order to test the truth of the proposition that if a card shows an even number on one face, then its opposite face is red? Show Hint Show Solution | Comments (3) | Be the first to vote Hint: A response that identifies a card that need not be inverted, or that fails to identify a card that needs to be inverted, is incorrect. The original task dealt with numbers (even, odd) and letters (vowels, consonants). Solution: The correct response is to turn over the 8 card and the brown card. The rule was "If the card shows an even number on one face, then its opposite face is red." Only a card with both an even number on one face and something other than red on the other face can invalidate this rule: If the 3 card is red (or brown), that doesn't violate the rule. The rule makes no claims about odd numbers. If the 8 card is not red, it violates the rule. If the red card is odd (or even), that doesn't violate the rule. The red color is not exclusive to even numbers. If the brown card is even, it violates the rule.
13. Bad School Boys During the lunch hour at school, a group of five boys from Miss Jones home room visited a nearby lunch wagon. one of the five boys took a candy bar without paying for it. When the boys were questioned by the school principal, they made the following statements in respective order: 1. Rex: "Neither Earl nor I did it." 2. Jack: "It was Rex or Abe." 3. Abe: "Both Rex and Jack are lying." 4. Dan: "Abe's statement is not true; one of them is lying and the other is speaking the truth." 5. Earl: "What Dan said is wrong." When Miss Jones was consulted, she said, "Three of these boys are always truthful, but everything that two of them say will be a lie." Assuming that Miss Jones is correct, can you determine who took the candy bar? Show Solution | Comments (8) | Be the first to vote Solution: Abe took the candy bar.
14. Oil Wells You are an oil mogul considering the purchase of drilling rights to an as yet unexplored tract of land. The well's expected value to its current owners is uniformly distributed over [$1..$100]. (I.E., A 1% chance it's worth each value b/w $1..$100, inclusive). Because you have greater economies of scale than the current owners, the well will actually be worth 50% more to you than to them (but they don't know this). The catch: although you must bid on the well before drilling starts (and hence, before the actual yield of the well is known), the current owner can wait until *after* the well's actual value is ascertained before accepting your bid or not. You want to maximize your profits. You didn't get rich by scoffing at small dollar amounts. A dollar is a week's wages. Bids must be in even rounded dollar values. How many dollars should you bid? Guess: Guess | Show Hint Show Solution | Comments (4) | Be the first to vote Hint: The seller will only sell to you if you bid either a fair price, or if you bid more than the well is worth to him. Solution: Bid $1 for a certain profit of 50 cents, assuming the seller will sell the well at a fair market price. If you bid $2 you may lose 50 cents or you may gain $1, and the average expected profit is only 25 cents. If you bid $3, you might break even, or you might lose $1.50 or you might gain $1.50, so the average expected profit is nothing. All other bids are losing propositions. The classic “winner’s curse” version often assumes values are continuous from $0 to $100. In that version, the right answer is bid $0, because every accepted bid has negative expected value.
15. You Are on Your Way to Salalalah You are on your way to Salalalah and it is midnight and you are in the middle of the dessert, when your tire goes flat. You remove the four bolts of your tire and keep them on the side of the road. Suddenly, a truck passes by at a very high speed and your bolts just go flying all over and you can't find them. What do you do to replace the tyre? You know there is a Tyre Repair Shop (equipment supplied by TTC ) about 20 KM away. As it is midnight no one will stop to help you. There are no camels around that you can ride and if you are thinking of using a flash light or wait till the sun rises hmmm its not the answer . Show Solution | Comments (4) | Be the first to vote Solution: Remove one bolt from each of the other tires and use them to secure the spare tire.
16. I Have a Bag, With Some Balls in it I have a bag, with some balls in it. All but 4 are blue, all but 4 are green, and all but 4 are red. How many balls do I have in total? Guess: Guess | Show Solution | Comments (10) | Be the first to vote Solution: The total number of balls in the bag is 6. You can have 2 blue, 2 green, and 2 red balls. This configuration satisfies the conditions that all but 4 are blue, all but 4 are green, and all but 4 are red.
17. Two Fathers Gave Their Two Sons Some Money. Two fathers gave their two sons some money. One gave his son 150 pesos and the other father gave 100 pesos to his son. When the two sons counted their money, they found that all together they had become richer by only 150 pesos. How come? Show Solution | Comments (4) | Be the first to vote Solution: The two fathers are actually a grandfather and a father. The grandfather gives 150 pesos to his son (the father), and then the father gives 100 pesos to his son (the grandson). Although the total amount given is 250 pesos, the increase in wealth is only 150 pesos because the father is also a son, and his original amount is not counted twice.
18. The Two Guards At the entrance to a building, two guards are standing outside. One guard is facing north, and the other guard is facing south. The guard facing north smiles. The other guard sees him and asks, “Why are you smiling?” How could the second guard see him? Show Solution | Comments (4) | Be the first to vote Solution: The two guards are facing each other, with one guard facing north and the other facing south. The guard facing north smiles because he is looking at the other guard, while the guard facing south is looking directly at him.
19. Arrange 10 Balls in 5 Lines Arrange 10 balls in 5 lines in such a way that each line contains 4 balls and only 4 balls. ● ● ● ● ● ● ● ● ● ● Show Solution | Comments (1) | Be the first to vote Solution: Arrange the balls in the shape of a pentagonal star, placing 4 balls at each of the intersecting points of the 5 lines. Each line formed by connecting the points of the star contains exactly 4 balls. 1 2 3 4 5 6 7 8 9 10
20. Where Must Dracula Be Exactly one casket holds Dracula.There are three caskets: one red, one yellow, and one blue.Each casket bears an inscription:Red: "Dracula is in this casket."Yellow: "Dracula is not in this casket."Blue: "Dracula is not in the red casket."At most one of these inscriptions is true.In which casket is Dracula? Show Solution | Comments (8) | Be the first to vote Solution: Assume Dracula is in the red casket.The red inscription is true.The yellow inscription ("Dracula is not in this casket") is also true because Dracula is in red, not yellow.That makes two true inscriptions, violating the rule. So Dracula is not in the red casket.Assume Dracula is in the blue casket.The red inscription is false.The yellow inscription is true, and the blue inscription ("Dracula is not in the red casket") is also true.Again there are two true inscriptions, which is impossible.The only remaining possibility is that Dracula is in the yellow casket.Here the red inscription is false, the yellow inscription is false, and the blue inscription is true—exactly one true statement, satisfying the condition.Therefore, Dracula must be in the yellow casket.
21. Spider on the Wall There are 5 girls over for a sleep over, one of the girls gasps and yells "OMG there's a spider on the wall" the other girls scream and yell "kill it." Yet the spider makes it outside alive. How is this? Show Solution | Comments (9) | Be the first to vote Solution: None
22. A Bag of Gold Coins I have 10 bags filled with 10 gold coins a piece, which equals 100 gold coins. 9 bags, are filled with counterfeit coins (90 total coins), while only 1 bag is filled with real coins (totaling 10 coins). They appear the same in shape, color, texture, and size. The only difference is their weight. Counterfeit coins weigh 1oz, while the real coins weigh 1.1 oz. Using a scale, only once, how would I determine which bag was filled with real coins? Show Solution | Comments (4) | Be the first to vote Solution: Take 1 coin from bag 1, 2 coins from bag 2, 3 coins from bag 3, and so on, until you take 10 coins from bag 10. Weigh all the coins together. The total weight will be 100 oz if all coins were counterfeit. For each bag, the excess weight over 100 oz will indicate the bag with real coins; for example, if the weight is 100.3 oz, then bag 3 has the real coins.
23. Dead Man A man is discovered hanging from the middle of an empty, windowless room. The door is locked from the inside, and the ceiling is too high to reach without aid. Apart from the rope around his neck, the only other thing in the room is a small puddle of water directly beneath him.How did he manage to hang himself? Show Hint Show Solution | Comments (8) | Be the first to vote Hint: He wasn't murdered, and there was no chair for him to get up and hang himself. :?: Solution: Before taking his life, the man brought a large block of ice into the room, stood on it, and fixed the rope to the ceiling. After he stepped off, the ice gradually melted, leaving only a puddle of water and no visible object he could have used to reach the rope.
24. You Are Shown a Set of Four Cards Placed on a Table You are shown a set of four cards placed on a table, each of which has a number on one side and a colored patch on the other side. The visible faces of the cards show 3, 8, red and brown. Which card(s) must you turn over in order to test the truth of the proposition that if a card shows an even number on one face, then its opposite face is red? Show Solution | Comments (9) | Be the first to vote Solution: You must turn over the card showing 8 to verify that it has red on the other side, as it is an even number. Additionally, you must turn over the brown card to ensure that it does not have an even number on the opposite side, which would violate the proposition. Turning over the card showing 3 or the red card is unnecessary, as they do not provide relevant information to test the proposition.
25. Mathematics.... Three men in a cafe order a meal the total cost of which is $15. They each contribute $5. The waiter takes the money to the chef who recognizes the three as friends and asks the waiter to return $5 to the men. The waiter is not only poor at mathematics but dishonest and instead of going to the trouble of splitting the $5 between the three he simply gives them $1 each and pockets the remaining $2 for himself. Now, each of the men effectively paid $4, the total paid is therefore $12. Add the $2 in the waiters pocket and this comes to $14.....where has the other $1 gone from the original $15? Show Solution | Comments (2) | Be the first to vote Solution: The confusion arises from the incorrect addition of the amounts. The three men paid a total of $12 after receiving $3 back ($1 each), and the waiter kept $2. The correct way to account for the money is to consider the total cost of the meal ($15) as $12 (paid by the men) plus $3 (returned to them), which equals $15. Therefore, the chef has $10, the waiter has $2, and the men received $3 back, with no dollar missing.
26. Brother's Age Difference You are 5 years old. Your brother is 15 years older than you. How old is your brother? Show Hint Show Solution | Add a comment | Be the first to vote Hint: Add the age difference to your current age. Solution: If the numbers are precise, your brother is 5 + 15 = 20 years old. If the numbers are rounded, your brother could be 5.9 + 15.9 = 21 years old.
27. Argots and Knicks Relationship Are all argots also knicks?1) All argots are drones2) All drones are knicks Show Solution | Add a comment | Be the first to vote Solution: Yes, all argots are knicks.
