I just do not believe the odds shown, or rather I find that the dice are almost always heavily loaded against me. I have just attacked a single Infantry unit, unpromoted, on a hill and not fortified (so strength 20+25% = 25) with two successive Tanks with Combat 2 (strength 28+20% = 33.6 each) and saw odds of about 85% in my favour for the first fight but lost my tank and reduced his strength in the process all the way down to an enfeebled 23 or so. Odds for second fight then over 90%; lost my second tank.Don't know if he had been damaged, because he vanished into the fog of war.
Other posters have reported losing fights at odds better than 100% and winning them at 0%. Poor me, I clearly come into the all-time-loser category.