Three are three vending machines. One delivers apple, second orange and third can deliver apple/orange when a coin is dropped in the machine. These machines are not yet labelled. Find out what is the minimum no of coins required to label them.

Answer is not yet known to me.

Questions by viveksri71

Showing Answers 1 - 9 of 9 Answers

mithr17

  • Dec 8th, 2011
 

The answer is 5 coins.

Reasoning:
For the sake of simplicity, I will name the machines as 1,2 and 3. At this stage, I do not know which machine give what fruits. I drop a coin in each of the machines, so thats 3 coins now. Lets say I got apple from #1, Orange from #2 and again an Orange from #3. I drop a coin each in any of the two machines out of the three. Lets say I dropped a coin in # 3 and #2 because I got Oranges in the first round. This way I would know which one gives just Oranges and which one gives both apples and oranges. Having labeled two machines, I can label the remaining machine - #1 - as apples because we only have 3 machines and the precondition tells us that there is one machine that gives just apples.

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Curtis

  • Oct 31st, 2017
 

4. One in each machine. The two that produced a pair, place a coin into one of them. If that one produces the other product you have your answer. If that one produces the same thing, then it will take more coins to figure out.

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viresh

  • Nov 21st, 2017
 

Answer is 5 since 3 coins are put in 3 respective machines then we get single fruit in each of machine and one more coin is needed to test whether machine gives different fruit. Still we need 1 more to check whether machine gives 1 more different fruit but it does not hence we need atleast 5 coins.

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