Probability question

Question

There is a 12% probability of a flood in Selangor this year. If a major earthquake does occur, the probability of a flood re-occuring the following year drops to 8%.

However, if there is no flood this year, the probability of a major earthquake next quake rises to 15%.

What is the probability if flood occurs twice in the next two years?

Answer 1

Hello Azwa A.,

What is the probability of what happening? A flood? A minor earthquake? A major earthquake?

From the probabilities supplied, there are no conclusions that can be established. Why?

You have a conditional probability for a flood next year only if there is both a flood and a major earthquake this year.

You have a probability of a flood this year.

You have a probability that if there is no flood this year, that the probability of the next minor quake becoming a major quake in any year (?) rises to 15%.

You have no data on the current yearly incidence of earthquakes, major or minor!

You have no data on the basal probabiity of a flood happening next year, if there is not a major earthquake this year.

And you want to know if something has a probability of happening if there are 2 floods (at any time?) within two years? I think there is -- all the survivors should immediately move to someplace else, where the disaster data is gathered and made public in a useful way!

-- Cheers, --Mr. d.