Puzzle of the Day : 44
Fake Diamond
A king wanted to marry off his daughter. Many suitors wanted to marry the princess. So, the king devised a competition to find the most worthy of them all. He put 27 identical looking diamonds in a box. He then announced that one of the 27 diamonds was a fake. The fake diamond was identical to the other diamonds in all respects except that it had a slightly different weight. The challenge was to find the fake diamond using only a simple pan balance. What is the minimum number of weighings required to find the fake? Provide a detailed explanation with your answer.
1
We have to find the minimum number of weighings, that will be the best case.
Answer is 2 because supposedly the weight donot come out to be the same in first attempt then in second attempt we can identify which one of the diamond is fake among the first two we have weighed.
Answer will be 2
If in our first attempt, there is a weight difference then we know one of them is fake, and in our second weighing we’ll know which of them are fake
3
1st weighing: Make groups of 9. Weight any two, if one side is heavier or lighter, the group contains the fake diamond. Otherwise, it’s the third group(the unweighted one) which contains the fake diamond.
2nd: Make groups of 3(Same process as above)
3rd: Weigh any two