Question 581680
Let {{{ a}}} = length
Let {{{ b }}} = width
Let {{{ c }}} = depth
The area to be tiled is:
{{{ a*b }}} floor
{{{ 2*a*c }}} a wall and opposite wall
{{{ 2*b*c }}} the other wall and opposite wall
If you double each dimension, you get 
{{{ 2*a*2*b + 2*2*a*2*c  + 2*2*b*2*c }}}
{{{ 4*a*b + 4*(2*a*c) + 4*(2*b*c) }}}
{{{ 4*( a*b + 2*a*c + 2*b*c ) }}}
This is 4 times the area of the 1st pool, so it will take
him 4 times as long to tile it, or
{{{3*4 = 12 }}} days