Let S1 and S2 be the two switches and let their probabilities of working be given by P(S1) = 4/5 and P(S2) = 9/10. Find the probability that the current flows from the terminal A to terminal B when S1 and S2 are installed in series, shown as follows:
Given: S1 and S2 are two swiches whose probabilities of working be given by
P(S1) = and P(S2) =
To Find: the probability that the current flows from terminal A to terminal B when
S1 and S2 are connected in series.
Now, since the current in series flows from end to end
the flow of current from terminal A to terminal B is given by
P(S1 S2) = P(S1)
P(S2)
=
=
Therefore, The probability that the current flows from terminal A to terminal B when S1 and S2 are connected in series is