The results reveal that it is possible (around a 5% chance) for a single chimp to type the word “bananas” in its own lifetime.

That sounds a little low to me. B and N are right next to each other, so I’d expect them to mash left and right among similar keys a lot of the time. Then again, I think we’re expecting some randomness here, not an actual chimp at a typewriter, but that’s probably more likely to reproduce longer works than an actual chimp.