Bottles and Pills Interview Puzzle
The Most Favorite Puzzle that is being asked in many MNCs Interview.
There are n (assume 10) bottles. In each bottle, there are identical balls weighing 1gm except one bottle which has balls of weight 1.1gm. find the odd bottle out?
Condition: You are permitted to use the weighing machine only once.
The solution is tricky, yet simple to understand.
-Place each bottle in a row and number them till n (10).
-Take 1 pill from bottle one, 2 pills from bottle two,… 10 pills from bottle ten.
-Weigh them on the weighing machine, and note down the reading as X. Assume computed value is 55.5
-Compute the notional value of all the weights assuming each bottle having 1gm pills as Y. i..e.. n(n+1)/2 or 10*11/2 = 55.
-Calculate deviation X-Y = 55.5 – 50 = 0.5.
-We get 0.5 when 5 balls of 1.1 (0.1) are taken from bottle five(n).
Hence the answer is bottle no: 5.