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**General Science / Re: How to combine probabilities?**

« **on:**10/11/2020 20:55:20 »

Quote from: alancalverd

the probability of a OR b is Pa + Pb...assuming that events a and b are mutually exclusive.

If a and b are independent events then you can get wrong answers.

For example if Pa=probability of rain today in the UK =70% (pardon my cynicism!)

Pb = probability that Coronavirus will be mentioned in the Newspaper = 99.99%

Then Pa + Pb = 70% + 99.99% = 170% (not possible)