i dont see the problem here, your average entry price is (A1+A2)/2 so your average profit is B-(A1+A2)/2=100 in this case , you traded two contracts so your total profit is 2x100= 200
Epic am afraid your calculations violate the laws of probability, if your probability of being correct is 50% then your overall profit expectation must be zero (neglecting commission charges), for you to have a positive expectation you must be correct more then 50%. You could apply your theory...