Need assistance with this hw prob:
A communication network has 5 links (see attach.)
The prob. that each link is working is 0.9. What is the prob of being able to transmit a message from point A to point B.
My attempt was to say, that the prob. of transmitting (TX) a message is the prob. of the top series link + prob. of middle + prob. of bottom - prob. of all 3. That is,
But that is > 1. Doh.
However, the approach I'd use is
Pr(successful transmission of message) = 1 - Pr(no transmission of message) =
and the last probability should be simple to calculate since (I assume) each series link is independent.