Question 758255
Visualizing and intuition show that the 27 marbles have 1 inch diameter.  The amount of water present in the cube will be volume of the cube minus volume of the twenty seven 1-inch-diameter marbles.  


The cube:  {{{3^3=37}}} {{{in^3}}}
The marbles: {{{27*(4/3)pi*(1/2)^3}}} {{{in^3}}}