perm and comb by aditya gopi - Tuesday, 31 January 2006, 9:44 PM Number of replies: 0 the work of 4 labourers can be checked by any one of the seven supervisors, then the probability that all the 4 labourers are checked exactly by two supervisors is (A) 32/343 (B) 2/7 (C) 12/49 (D) 6/49 Permalink Reply