Answer:
20 possible arrangements
Step-by-step explanation:
A: Alice
B: Bob
C: Cindy
X: other student
All the possible arrangements are:
When Bob is in the first place
B A C X X
B A X C X
B A X X C
B X A C X
B X A X C
B X X A C
6 possible arrangements
When Bob is in the second place (notice that neither Alice nor Cindy can be before Bob)
X B A C X
X B A X C
X B X A C
3 possible arrangements
When Bob is in the third place
X X B A C
Only 1 possible arrangement.
Total arrangements when Bob is before Cindy: 10
If Cindy is before Bob the same situations are repeated, given another 10 arrangements. So, the total line up in which Alice is somewhere between Bob and Cindy are 20.
