- #1
danago
Gold Member
- 1,123
- 4
A subgroup must be formed, with 4 people being chosen from 3 larger groups.
The subgroup of 4 must contain atleast 1 person from each group (A,B,C). How many possible groups are there?
Well there are 6 possible choices for the first place, 4 for the next and 3 for the third place. The fourth place can be taken by any of the remaining 10people. The calculation i came up with was:
[tex]
{}^6C_1 {}^4C_1 {}^3C_1 {}^{10}C_1=720
[/tex]
However, that is wrong. What have i done wrong?
- Group A contains 6 people
[*]Group B contains 4 people
[*]Group C contains 3 people
The subgroup of 4 must contain atleast 1 person from each group (A,B,C). How many possible groups are there?
Well there are 6 possible choices for the first place, 4 for the next and 3 for the third place. The fourth place can be taken by any of the remaining 10people. The calculation i came up with was:
[tex]
{}^6C_1 {}^4C_1 {}^3C_1 {}^{10}C_1=720
[/tex]
However, that is wrong. What have i done wrong?