<p>A large cube with edge of 3 units is built from 6 small blue unit cubes and 21 small white unit cues. What is the greatest possible fraction of surface area of the large cube that could be blue?
a)1/9 b) 2/9 c) 1/3 d) 4/9 e) 2/3</p>
<p>I did it in every possible way, and I always got 16/54 max.. </p>
<p>the answer is c) 1/3 though o.O</p>