Which is Heavier?

Once, Krishna’s mother took him to a grocery store to bring some items. The mother was telling the shop owner that her son got 100 out of 100 in Mathematics in 10th Standard final examination. The shop owner thinking that Krishna knew only the contents of the Mathematics text book and nothing extra asked a question to test him. The question was: “I would give you 87 identical items weighing 136 grams each. Among these items, there is one item which weighs 141 gram. There is no way to determine the heavier item without a weight balance. Given a weight balance what is the minimum number of weighings needed to find out the heavier item?” Before the shop owner completed his question Krishna answered. The shop owner appreciated Krishna for his brilliance. He also gave Krishna a parker pen freely.

Can you answer the shop owner’s question?


Hint

The answer is less than 7. Try to find out the number of weighings needed to find a heavier item when there are three items. Then attempt for 87 items.


Answer

5.