AMC 12A 2008 Problem 21

A permutation \left(a_{1}, a_{2}, a_{3}, a_{4}, a_{5}\right) of (1,2,3,4,5) is heavy-tailed if a_{1}+a_{2}<a_{4}+a_{5}. What is the number of heavy-tailed permutations?

Answer Choices
A. 36
B. 40
C. 44
D. 48
E. 52