Oy folks, this is my first time on this forum as well as my first post, so I'm automatically going to assume I'm posting in the wrong place and will break one rule or another through the course of this post. Let me know and I'll do my best to fix anything wrong.

Back to the question at hand - how can I calculate aggregate expected value for multiple final score lines at the same time?

For example, given:

Match: Borussia Dortmund v. Werder Bremen 8/23/13

Relevant Final Score Odds:
BVB 4-0 = 10/1
BVB 4-1 = 14/1
BVB 4-2 = 33/1
BVB 4-3 = 66/1
BVB 5-0 = 20/1

Aggregate Probability of Final Score being any of these lines: 30%

Assuming my probability is correct, how would I calculate the EV of the five lines together?

My approach was to first find the mean of the odds, which in the above example is 28.6/1.

Then I used that for a basic EV calculation: (24.6*0.3)-(5*0.7) = 3.88

To find the amount won I used the 28.6/1 average, minus 4 to get 24.6, because winning one bet means losing the other four.

This is obviously an absurdly large EV. At first I was like "muhuhu, looks like the bookies lines are inefficient when it comes to the lower volume team props." But now I'm pretty sure my calculations were wrong, with the first misstep being using the simple mean of the different lines rather than a weighted one. Problem being the handicapping analysis I'm relying on only lists an aggregate probability for final scores where one team scores 4 or more. Without individual %'s for these lines there's no way to weight each one.

So, bottomline, am I asking an impossible question given the information above? Is there any way to bet the above lines profitably given said information (perhaps changing betsizes according to the individual lines)? Usually with such a dearth of information I'd just walk away from the bet, but with lines that meaty and a trusty probability of success of 30%, I thought I'd at least throw it out there for someone to wrestle with.