1) The number of people in the group must divide 40. 8 is the only selection that divides 40.
2)
Even sum pairs are (1,1),(4,4),(4,6),(4,8),(6,4),(6,6),(6,8),(8,4),(8,6),(8,8) - There are 10 of them
Odd sum pairs are (1,4),(1,6),(1,8),(4,1),(6,1),(8,1) - There are 6 of them
P[Even]=10/16 = 5/8
P[Odd]=6/16 = 3/8
E[moves] = 5/8 x 6 - 3/8 x 2 = (30-6)/8 = 3 = 3 spaces forward