CAYLEY 2008 Problem 25

Past Contests CAYLEY CAYLEY - 2008
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1

The average value of (a-b)^2+(b-c)^2+(c-d)^2+(d-e)^2+(e-f)^2+(f-g)^2 over all possible arrangements (a,b,c,d,e,f,g) of the seven numbers 1,2,3,11,12,13,14 is

Answer Choices
A. 398
B. 400
C. 396
D. 392
E. 394