Question d'entretien d'embauche FDM Group: You have 20 balls all equal i... |

Question d'entretien d'embauche

Entretien de Applications Support Analyst/Consultant Toronto, ON

You have 20 balls all equal in size. They all weigh the

  same except for one. How do you identify the one that weighs less or more?

Réponse de l'entretien

4 réponses


• Break the balls into the following groups: (1, 2, 3), (4, 5, 6), (7, 8)
• Step 1. Weigh (1, 2, 3) against (4, 5, 6)
Two possible outcomes:
The two groups are equally heavy. (Case A)
One of these groups is heavier than the other. (Case B)

• Case A >> Weigh 7 against 8. Now you have identified the heavier ball in 2 weighing.
• Case B >> Take the heavier group (assume it to be (1, 2, 3)), take any two balls and weigh them against each other. Either one of these is heavier else the third ball is.

Mohammed, le 21 avr. 2014

The above answers is for 8 balls.

Utilisateur anonyme, le 15 juill. 2015

The above answer doesn't work. The unique ball can weigh less or more than the other balls. You assumed the unique ball is the heavier one.

Utilisateur anonyme, le 15 juill. 2015

If we can do as many times as we want, just random pick 2 balls. If they have equal weight, compare with the rest. If not, just pick the third one to find out which One is the exception.

Utilisateur anonyme, le 18 sept. 2015

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