Question 164173
(a) 8 * 7 * 6 = 336 ways


(b) use combination: 
    {{{C(8,3) = 8!/((8 - 3)! * 3!)}}}
    = {{{8 * 7 * 6 * 5!/(5! * 3 * 2 * 1)}}}
    = {{{8 * 7 * 6/6)}}}
    = 8 * 7
    = 56 groups