2004 · Q80
80. Amit has 7 friends whom he wishes to invite to a dinner. Out of his 7 friends, 1 or more may accept the invitation. In how many different ways can Amit's 7 friends attend the party?
MathematicsCombinatorics
- A96
- B112
- C127
- D128
Explanation
Any non-empty subset of the 7 friends may accept the invitation. The number of non-empty subsets of a 7-element set is 2⁷ − 1 = 128 − 1 = 127.