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A forger Weighing puzzles  Weight: 1 Liked the puzzle: 87% 27.12.2009
A Megamind owns a mint with a 100 workers. Each day, he gives 1kg of gold to each worker, and each worker must make 100 coins (10 grams each). The Megamind learnt that one nof the workers is a forger, he makes coins that are 1g lighter. How can Megamind determine the forger using only one weighing? The scales can determine the total weight, up to 100 kg.
Comments:  1 | check your solution  
8 coins Weighing puzzles  Weight: 1 Liked the puzzle: 100% 30.12.2009
You have 8 coins that appear to be identical, except one (which is counterfeit) is slightly heavier than the others. What is the minimal number of weighings on the balance scale that is required to find the counterfeit coin?
Comments:  1 | check your solution  
Defective balls Weighing puzzles  Weight: 1 Liked the puzzle: 100% 03.02.2011
A Megamind has ordered a set of steel balls for his scientific experiments: 2 red, 2 orange, 2 yellow, 2 green, and 2 blue. The order was fulfilled but the balls of some color were made 1g lighter than the others. The Megamind has a balance scale that shows the exact weight differential between the two cups. He needs to determine the defective color using one weighing. Please, help the Megamind to do this.
Comments:  1 | check your solution  
Laundry Weighing puzzles  Weight: 1 Liked the puzzle: 83% 19.03.2011
A Megamind was doing his laundry. The washer's manual says that a standard load of detergent is 220 g. The Megamind has a bag of dry detergent containing exactly 1 kg, the balance scale, and four weights: 2x10 g and 2x5 g. How can the Megamind obtain exactly 220 grams of detergent using at most three weighings?
Comments:  1 | check your solution  
101 coins Weighing puzzles  Weight: 3 Liked the puzzle: 100% 04.01.2010
Among 101 coins, exactly 50 are counterfeit. A counterfeit coins weighs one gram more or gram less than the real coin (counterfeit coins may weigh differently). You have a balance scale that shows the exact weight differential between the two cups. How can you determine whether a given coin from this set is counterfeit using the scale only once?
Comments:  1 | check your solution  
Weights Weighing puzzles  Weight: 3 Liked the puzzle: 100% 29.01.2010
What is the minimal number of weights required to be able to balance all integer weights 1,2,...,40 on a balance scale? Justify the minimality.
Comments:  4 | check your solution  
12 coins Weighing puzzles  Weight: 4 Liked the puzzle: 100% 03.02.2010
A Megamind has 12 coins, one of which is counterfeit and weighs differently from the others. He has a balance scale, but no weights. How can the Megamind find the counterfeit coin and determine whether it is lighter or heavier than the standard ones? What is the minimal number of weighings required?
Comments:  1 | check your solution  
18 crystals Weighing puzzles  Weight: 5 Liked the puzzle: 100% 30.12.2009
Once upon a time, a Megamind worked as an optometrist for an Occupier who was color blind. The Occupier had a dream that he may regain perfect vision if the Megamind made him a set of 9 red and 9 blue crystals. The crystals should be of the same size, but the blue ones should be heavier than the red ones. Crystals of the same color should weigh the same. The Megamind completed the order and brought two sets of crystals: blue in his right hand and red in the left. The Occupier was suspicious, he did not trust the Megamind. Fortunately, the Occupier has a balance scale. How can the Megamind convince the Occupier that all crystals in one hand are blue and in the other - red. He can use no more than three weighings.
Comments:  5 | check your solution  
Correct labels Weighing puzzles  Weight: 5 Liked the puzzle: 100% 08.01.2010
There are six weights 1,2,3,4,5,6 grams. They are labeled with numbers 1,2,3,4,5,6. Some may be mislabeled. How can you determine whether all labels are correct using a balance scale? What is the minimal number of weighings?
Comments:  1 | check your solution  



 
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