Question 791038
4 pipes a,b,c,d can fill a tank in 3,6,9,12 days respectively.
 what is the least portion of tank that can be filled in one day by any three of pipes working together at their respective rates?
:
{{{1/12}}} + {{{1/9}}} + {{{1/6}}}
Common denominator is 36
{{{3/36}}} + {{{4/36}}} + {{{6/36}}} = {{{13/36}}}th of the tank