2016 · Q10
Let A = {7, 8, 9, 10, 11, 12} and B = {7, 10, 14, 15}. What is the number of elements in (A-B) and (B-A) respectively ?
Elementary MathematicsSet Theory
- A2 and 4
- B4 and 2
- C2 and 2
- D4 and 4
Explanation
A−B removes the shared elements 7 and 10, leaving {8,9,11,12} — 4 elements. B−A removes the same shared elements, leaving {14,15} — 2 elements. So the counts are 4 and 2 respectively (option B).