The seven digits \(1,1,2,3,4,5,6\) are arranged in a random order in a line. Find the probability that they form the number 1452163.
Three of the seven digits \(1,1,2,3,4,5,6\) are chosen at random, without regard to order.
(a) How many possible groups of three digits contain two 1s?
(b) How many possible groups of three digits contain exactly one 1?
(c) How many possible groups of three digits can be formed altogether?