You have 10 boxes of golf balls (each ball weighing exactly 10 gm) with one box with defective balls (each one of the defective balls weigh 9 gm). You are given an electronic weighing machine. How will find out which box has the defective balls? How many chances will you take to weigh?

**Possible Solution:**

**If you are thinking along the lines of weighing one ball from each box in whichever fashion, believe me you are thinking in wrong direction. The answer is**

**one.**Yes ! Read on to find out how…

The trick here is to take different balls from different boxes. First you need to number each of the boxes from 1 to 10. Now take out 1 ball from box #1, 2 from box #2… 10 from box #10

Now we have total of 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 = 55

So total weight now should be 55 * 10 = 550 gms.

Now suppose box #7 had defective balls. So when you weigh the 55 balls together, the weight would be 7 * 1 = 7 gms less. i.e. 543 gm.

This way you can find out the right box with defective balls.

So if the weight is (550 –

**x**) gms,

**x**is the defective box #.

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