Probability
Two adults a1 and b1, and eight children c1, c2, ... , c8 board a bus with 10 seats s1, s2, ... , s10. The adults board first and randomly select seats. The children select seats in order with c1 selecting first, c2 selecting second, and so on. Each child sits in the lowest numbered seat available to them. What is the probability that c7 sits in s8?