Relative Order of Three Objects

The other three objects do not affect the relative order of A, B and C.

All orderings of A, B and C among themselves are equally likely.

1. 1. Reduce to three objects

   By symmetry, the relative order of A, B and C is uniform over the $3!=6$ possible orderings.

   $$P(\text{any fixed order})=\frac{1}{6}$$

2. 2. Select the target order

   Exactly one ordering matches A before B before C.

   $$P=\frac{1}{3!}=\frac{1}{6}$$

Answer: 1/6