The Defective Chocolate | Puzzle 9

Question

You have ten boxes and an electronic weighing machine. In those ten boxes, you have chocolates. Each chocolate weighs 20 gram. But in one box the chocolates are defective and each weighs 19 gram exactly. 

Now you can weigh in the electronic weighing machine but you can use that machine just once. 

How will you find out which box has the defected chocolates?

Solution

If you are thinking to hold one chocolate from each box in hand and then balancing weight in bare hands, you are thinking all wrong. 😜

Let us begin by labeling the boxes as 1, 2, 3, ...... till 10.

Now, pick one chocolate from box 1, two chocolates from box 2, three from box 3 and so on. In total, you will have 55 chocolates now. (1 + 2 + 3 + ..... + 10)

The ideal weight of the chocolates should be 55 * 20 = 1100. However, somewhere in there are the defected chocolate/s.

You can judge that clearly by noting down the result of 1100 - total weight of chocolates. If the weight is less than 1 gram, the defected box is box 1, if the weight is less than 2 grams, the defected box is box 2 and so on.

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