A committee is to be made up from a group of 10 candidates. The committee must consist of a chairman and some (not necessarily nonzero) number of members-at-large. How many ways can the committee be chosen? (For example, suppose that Alex is chair while Betty, Carl, and D'Angelo make up the committee. This counts as the same as Alex being chair while Carl, Betty, and D'Angelo make up the committee. It is not the same as Betty being the chair, with Alex, Carl, and D'Angelo making up the committee. It is also not the same as Alex being chair with the committee consisting of Betty and Carl.)
A committee is to be made up from a group of 10 candidates. The committee must consist of a chairman and some (not necessarily nonzero) number of members-at-large. How many ways can the committee be chosen?
Chairman+0 10 = 10 ways
Chairman+1 10*9 = 90 ways
Chairman+2 10*9C2 = 10*36 = 360 ways
Chairman+3 10*9C3 = 10*84 = 840 ways
Chairman+4 10*9C4 = 10*126 = 1260 ways
Chairman+5 10*9C5 = 10*126 = 1260 ways
Chairman+6 10*9C6 = 10*84 = 840 ways
Chairman+7 10*9C7 = 10*36 = 360 ways
Chairman+8 10*9C8 = 10*9 = 90 ways
Chairman+9 10 = 10 ways
Now you can add up all the ways :)
A committee is to be made up from a group of 10 candidates. The committee must consist of a chairman and some (not necessarily nonzero) number of members-at-large. How many ways can the committee be chosen?
Chairman+0 10 = 10 ways
Chairman+1 10*9 = 90 ways
Chairman+2 10*9C2 = 10*36 = 360 ways
Chairman+3 10*9C3 = 10*84 = 840 ways
Chairman+4 10*9C4 = 10*126 = 1260 ways
Chairman+5 10*9C5 = 10*126 = 1260 ways
Chairman+6 10*9C6 = 10*84 = 840 ways
Chairman+7 10*9C7 = 10*36 = 360 ways
Chairman+8 10*9C8 = 10*9 = 90 ways
Chairman+9 10 = 10 ways
Now you can add up all the ways :)