A factory manufacturing flywheels for racing cars has 10 machines to make them. The manufacturer knows the correct weight for a flywheel.However, one day one of the machine begins to produce faulty parts- either overweight or underweight.How can the manufacturer find the faulty machine in only 2 weighings

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Questions by Pooja Gupta84   answers by Pooja Gupta84

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Archana.G

  • Oct 6th, 2006
 

Hi pooja,

Proceed this way..........

Take 1 fly wheel from 1st machine ,2 flywheels from  2nd, 3 from 3rd and so on 10 from the 10th machine.Now u will have a total of 55 wheels.

just weigh them.say you got "y"

Now as u know the actual weight of a wheel say some "x" then weight of 55 wheels must be 55x.

Now ((y ~55x) / x) gives the machine which shows the faulty weight.

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Rathinavelu

  • Oct 23rd, 2006
 

As Archana said, find y.

For second weighing, take one sample from each machine and find its weight, let it be z,

The weight of each sample is x, therefore the actual weight should be 10x

find (z~10x)  --> difference between original and faulty sample.

Now perform ( y ~ 55x)/(z ~10x) to find out the faulty machine.

Note: Thanks for Archana, her approach helped me to solve this problem.

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