 #1
songoku
 2,130
 283
 Homework Statement:
 Please see below
 Relevant Equations:

Probability
Arithmetic Sequence
I try to list all the possible sequences:
1 2 3
1 3 5
1 4 7
2 3 4
2 4 6
2 5 8
3 4 5
3 5 7
4 5 6
4 6 8
5 6 7
6 7 8
I get 12 possible outcomes, so the probability is ##\frac{12 \times 3!}{8^3}=\frac{9}{64}##
But the answer key is ##\frac{5}{32}## . Where is my mistake? Thanks