Question

The probability of a major earthquake on a given day is 1 out of 10000. WHat is the expected number of major earthquakes in the next 100 days?

Answer 1

if one day is 1:10000 then 10o days should be 100:10000 or 1%

Answer 2

Probability of no major earthquake in 1 day is: \[\large 0.9999\]

Probability of no major earthquake in 100 days is: \[\large (0.9999)^{100}\]

so probability of an earthquake in 100 days is 1 minus that. You get 99.5 out of 10000. Close to 1% but not quite.