novice excel user trying to find what function i use to calculate the
probability of something happening in either year 1 or year 2 where the
probability is 5% in yr1 and 10% in yr2

grahog -

This is more of a basic probability question than an Excel question.

That is, there are no specific Excel functions for this. Just use your own
worksheet formulas.

Assuming independence,

Prob(it happens in either year 1 or in year 2 or in both) =

1.0 - Prob(it doesn't happen in either year) =

1.0 - Prob(doesn't happen in year1)*Prob(doesn't happen in year 2) =

1.0 - 0.95*0.9 =

1.0 - 0.855 =

0.145

Or, Prob(it happens in year 1 or it happens in year 2 but not in both) =

Prob(happens in year 1 but not in year 2) + Prob(happens in year 2 but not
in year 1) =

0.05*0.9 + 0.10*0.95 =

0.045 + 0.095 =

0.140

- Mike
http://www.mikemiddleton.com

"grahog" wrote in message
...
novice excel user trying to find what function i use to calculate the
probability of something happening in either year 1 or year 2 where the
probability is 5% in yr1 and 10% in yr2