

InterviewSolution
Saved Bookmarks
1. |
Let A and B two sets containing four and two elements respectively, The number of subsets of the set A × B, each having at least three elements is:1. 2702. 2393. 2194. 256 |
Answer» Correct Answer - Option 3 : 219 Concept: Selection r things out of n things is denoted by nCr nCr = \(\rm \frac {n!}{(n-r)!r!}\)
Calculation: Set A has 4 elements Set B has 2 elements Total number of element in (A × B) = 4 × 2 = 8 Total number of subsets of (A × B) = 28 = 256 Number of subsets having 0 element = 8C0 = 1 Number of subsets having 1 element = 8C1 = 8 Number of subsets having 2 elements = 8C2 = (8 × 7)/2 = 28 Number of subsets having at least 3 elements = 256 – 28 – 8 – 1 = 219 Hence, option (3) is correct. |
|