What are the odds on the slot machines?

Solution 1:

Here is a pie chart and list with all items / probabilities:

^{Source: Orcz Wiki, "Borderlands 2: Moxxi Slot Machines Odds Probabilities Statistics"}

These are the results of spinning the Slot Machines from Borderlands 2 at Moxxxis 22,362 times:

Detailed Results (Combination, Prize, Number of Spins, Percentage) from most frequently occurring to most rarely occurring:

TOTAL SPINS: 22,362

2 Same Symbols With Bell - (Cash) 5216 (23.33%)
No Match - 4708 (21.05%)
2 Same Symbols Without Bell - (White Weapon) 4513 (20.18%)
3 Cherries - (Green Weapon) 3179 (14.22%)
3 Psychos - (Live Grenade) 2387 (10.67%)
3 7s - (Custom Skin) 981 (4.39%)
3 Single Eridium - (4x Eridium) 602 (2.69%)
3 Moxxi Legs - (Blue Item) 327 (1.46%)
2 Bells - (Cash) 190 (0.85%)
3 Double Eridium - (8x Eridium) 165 (0.74%)
3 Marcus - (Purple Weapon) 41 (0.18%)
3 Triple Eridium - (12x Eridium) 39 (0.17%)
3 Bells - (Lots of cash) 9 (0.04%)
3 Borderlands Vault Symbol (JACKPOT) - (Orange Weapon) 5 (0.02%)

Found this while doing a quick search for the statistical numbers. There is also a chart that shows the different percentages for each of them.