Interview Question

Q & A Analyst Training Program Interview(Student Candidate) Boston, MA

Scenario: You have 8 golf balls and 1 is heavier than the

  7 others. All you have is a balance used in chemistry classes. What is the shortest number of times you could measure the golf balls to find the heaviest ball?
Tags:
logic
Answer

Interview Answer

5 Answers

0

You have to keep in mind that you're dividing up the balls. They try to confuse you, but just ignore the people and stick to your intuition. The quickest way to discover the heaviest ball was in 2 steps.

Interview Candidate on Apr 26, 2010
0

i would say three. you could put 4 balls on each side and then take the heavier side. split that group into two balls on each side. then lastly split that group to have one ball on each side.

Anonymous on May 2, 2010
0

i would say three. you could put 4 balls on each side and then take the heavier side. split that group into two balls on each side. then lastly split that group to have one ball on each side.

Anonymous on May 2, 2010
7

2 steps.

1. Put 3 balls on each side of the scale measure( [123], [456] )
If each group of 3 is equal:
2. Place the remaining two balls on the scale - measure( [7], [8] )
If each group of 3 is not equal: assuming [123] is heavier than [456]
2. Take 2 balls from the heavier group from step 1 and place them on the scale. measure( [1], [2] )
If they are equal then [3] is the heaviest

Brian on Nov 18, 2010
0

3 v. 3

Case 1: Heavier ball lies within the first 3v3 weighing. Weigh 2 of the balls on the heavier side. Either one is heavier or they balance. If they balance, then it's the 3rd one we didn't weigh. Done.

Case 2: 3v3 balances. Then the heavier ball lies within the other 3 not weighed. Weigh 1v1, either it balances or it doesn't. If it doesn't, we're done because we can see that one side is heavier. If it does, then it's the third one not being weighed.

Minimum amount of weighings is 2.

Anonymous on Feb 7, 2013

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