UPSC NDA Math Model Paper 3

The given set contains 8 elements given as U = {1, 2, 3, 4, 5, 6, 7, 8}.
Number of ways of withdrawing the first number is 8C1=8.
Since, we are not replacing the first number, for selecting the second number we are left with only 7 choices.
Number of ways withdrawing the second number is 7C1=7.
Thus, number of elementary events in the sample is same as withdrawing number once and then the second time.
Therefore, required number is 8 × 7 = 56.