Question 498090
16C4 ways to draw 4 chips


___ 7*3*(6C2) ways to draw r-w-b-r
___ 6*3*(7C2) ways to draw r-w-b-w
___ 6*7*(3C2) ways to draw r-w-b-b


___ [(21*15)+(18*21)+(42*3)] ways to draw 4 with all colors


P = [(21*15)+(18*21)+(42*3)] / 16C4