Deciding the major product in this Wurtz reaction
I think that there should be a 'statistical product distribution', if I'm correct the products should be in the ratios 2:1:1.

You get to this conclusion as follows, call 2-chlorobutane A and 2-chloropropane B.

A can react with A to give AA, and
A can react with B to give AB, while
B can react with A to give BA, while
B can react with B to give BB.

When you realise that AB and BA are the same molecule you get AA:2AB:BB; that is, 1:2:1.