   # Given 27 table tennis balls, one is heavier than the others.........

0 votes
354 views

Given 27 table tennis balls, one is heavier than the others.
What is the minimum number of weighings (using a two-pan balance scale) needed to guarantee identifying the heavy one? Of course, the other 26 balls weigh the same. posted Nov 12, 2014
Share this puzzle

## 1 Answer

0 votes

3 steps as below. The heavy weight has the heavy ball. In case they are equal, the heavy ball is in the group left on the side.
Step 1. weight 9+9, leave 9 on the side, with the heavier group go to step 2
Step 2. weight 3+3, leave 3 on the side, with the heavier group go to step 3
Step 3. weight 1+1, leave 1 on the side. answer Sep 3, 2018

Similar Puzzles
0 votes

Suppose you’re on a game show, and you’re given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1.

Now the host, who knows what’s behind the doors, opens another door, say No. 3, which has a goat. He then says to you, “Do you want to switch and pick door No. 2?”

What would you do?

0 votes

Five parcels labelled A, B, C, D and E weigh 60 kg. When arranged in a certain order, each weighs 1kg heavier than the one before it. E is 1kg heavier than A which is 2kg lighter than B. D is 1 kg lighter than C, which is 3 kg heavier than E. Write down the order.

0 votes

You start with small and equal cubes, 27 of which are put together to form a large cube. How does one then remove 1 from the middle of the large cube to leave only 26, while not touching any of the sides of the large cube?

–1 vote

If the digits of a two-digit number are interchanged, the obtained number is 27 more than the original number. The digits of the number are in the ratio of 2 : 1, then
What is the original number?

+1 vote

Five mums each have four sons that each have three tennis balls.
If a half of a half of the tennis balls are not green, how many of the tennis balls are green?