How many different people die from a ruptured appendix?

Not uncommon: About 7% of the population will develop acute appendicitis in their lifetime. Of these, about 15% of appendicitis will have ruptured or perforated at the time of appendectomy. Of these, about 2% will die from complications from ruptured appendicitis, especially in those patients with other medical conditions, very old and very young patients.

Much less today. : At least in developed countries the numbers are much smaller than a hundred years ago. Still, it can happen in older patients where other diseases may hide the diagnosis from doctors until it's too late.