Thursday 20 August 2015

mathematics - Find the Different Sugar Cubes




There are 10 Boxes, each contains 1000 sugar cubes. The sugar cubes in 9 of the boxes are 10 grams each and the other box has 9 gram cubes.


There is a digital scale that you can use it ONCE. (i.e. put something on the scale, turn it on and read the number)


Find the box with the 9 gram cubes.


Source: Fekraneh.ir



Answer




  • Set number from 1 to 10 to each box.

  • pick cubes from from boxes with the equal amount of number of each box, and put them on scale.



  • read the last digit of shown number on the digital scale, and subtract this amount from 10. (e.g. weight=543 grams => 10 - 3 = 7 )


    The signle digit result will lead us to the 9 gram cubes box




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