Expondist function...

[KyWilde]

mean = 33 days, what's pdf of success in 40 days...

I keep getting .009 and that seems low. Am I using this function incorrectly?

 

[Michael R Middleton]

KyWilde -

mean = 33 days, what's pdf of success in 40 days... I keep getting .009
and that seems low. Am I using this function incorrectly? <

Yes.

If X is an exponentially-distributed uncertain quantity (random variable)
with Mean(X) = 33, then the parameter for Excel's EXPONDIST function is
Lambda = 1/Mean(X) = 1/33.

P(X<=40) = EXPONDIST(40,1/33,True) = 0.70243459

- Mike

www.mikemiddleton.com