Question 1149749
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The side of the cube is  {{{root(3,216)}}} = 6 cm.


Let h be the water level in the contender originally.

Notice it became 6 cm after the cube was placed in the container.


So, the original water volume in the container was  {{{V[1]}}} = 10*12*h cm^3.


After placing the cube, the volume of water is  {{{V[2]}}} = (10*12*6 - 216) cm^3.


Both volumes are the same,  {{{V[1]}}} = {{{V[2]}}},  which gives you an equation for h


    10*12*h = 10*12*6 - 216,   or

    120h    = 504

       h    = {{{504/120}}} = {{{42/10}}} = 4.2 cm.    <U>ANSWER</U>
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Solved.