If I haven't completely mangled this then, the probability of
surviving through TWO sequential occurrences of an event, each
occurrence of which carries a 9-in-10 probability, is:

.9 * .9 = .81

If one were to survive through these two trials and try a third
the odds of surviving all three would be:

.9 * .9 * .9 = .729

Doesn't look good for an event with a 1-in-10 chance of dying!

Have I got this sorted out?

Yep.

And you even got the part about multplying survival rates rather than
death rates (a sometimes subtle point - the sequence depends on multple
survivals, not multple deaths)

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.