In how many ways can four boxes of chocolate be chosen from a store with 10 different selections if at least two of the boxes are of the same type?
okay for this one, i counted cases
1) all 4 the same: 4C4
2) 3 same, 1 different : 4C3 x 7C1
3) 2 same : 4C2 x 8C2
and then i just add these but apparently the answer is 505 so i'm confused.
okay for this one, i counted cases
1) all 4 the same: 4C4
2) 3 same, 1 different : 4C3 x 7C1
3) 2 same : 4C2 x 8C2
and then i just add these but apparently the answer is 505 so i'm confused.