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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,496

hi Den,

It looks like this is a binomial probability question. http://www.mathsisfun.com/data/binomial … ution.html

If p is the probability of one network working, then the probability of exactly M working out of N is

where

But you would also be happy if more than M are working so you need to add up all Ps from M up to N:

Hope that's what you wanted.

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Sometimes I deliberately make mistakes, just to test you! …………….Bob Bundy

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