There are three students, A, B and C, who want to take part in the speech contest. The order of their participation was decided by drawing lots. As a result, the order of the contest happened to be A, B and C.
∵ There are six cases in the order of A, B and C, and there is just one case of A, B and C..
The probability that it happens to be a, b and c is 16.
So the answer is: 16.