Huh. Gunder's experience makes me think that the drop rate on those Zombie Ribs could use a second look.

Yes, there's probability involved, but what is the probability of not looting a rib until the 55th consecutive kill?

Assume that:
1. The expected drop rate for Zombie Ribs is 10% (1 in 10 kills).
2. Loot is randomly selected every time (events are independent).

That means that there is a 90% chance of not looting a rib at each kill.

The probability of looting a rib on the 2nd kill is the probability of not looting a rib on the first kill, times the probability of looting a rib on the 2nd kill: 9%. (90% * 10%)

The probability of looting a rib on the 3rd kills is the probability of not looting a rib on the first and second kill, times the probability of looting a rib on the 3rd kill: 8.1%. (90% * 90% * 10%)

Thus, the probability of looting a rib on the 55th kill is the probability of not looting a rib on the first 54 kills, times the probability of looting a rib on the 55th: 0.033% (90% ^ 54 * 10%)

We know that the first rib drop was at the 55th kill, so the above scenario did, in fact happen. Either Gunder has been extremely (un)lucky or one or both of the assumptions are wrong.

Of course, I could be wrong with my use of statistics, in which case I'd appreciate a correction and explanation.