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You have 9 lemons, which all look exactly same. Same height, same color... There is no visible difference between any of them.

All lemons weigh the same amount, except for one, which weighs a little less than the others.

You are allowed to use a scale to compare weight, but you can only use the scale at maximum 2 times.

Can you find the lemon that weighs less than the others?

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  • $\begingroup$ well, lemons are the same colour as gold coins... $\endgroup$
    – Jasen
    Nov 22, 2017 at 10:52

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It could be

Take groups of 3 lemons each (say A, B and C) and weigh which should provide you the required lemon

As,

First weight two groups of 3 lemons each - say A and B. If they turn out to be same weight - which indicates that the required lemon is not in either of these groups. Then weight two lemons of group C - which can result in lemons of same weight being weighed - means the left out one is the required one otherwise it shows up in the balance.

If

both the groups A and B do not weigh the same, identify the lesser weighing group (say B) and weigh two lemons of B and repeat the above process to find out the less weighing lemon.

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  • $\begingroup$ You could add explanation as to how you determine which group it is in based on the results of the weighing. Although it it seemingly obvious, it would explain the full process to your result. Same with then weighing the remaining Lemons. $\endgroup$
    – IAmGroot
    Nov 22, 2017 at 11:03

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