# Math Help - cant be done

1. ## cant be done

A boiler has five identical relief vavles. The probability that any particular vavle will open on demand is .95. Assuming independent operation of valves, caculate P(at least one vavle opens) and P(at least
one valve fails to open).

Can u help me by showing how to do this?

2. Originally Posted by statman101
A boiler has five identical relief vavles. The probability that any particular vavle will open on demand is .95. Assuming independent operation of valves, caculate P(at least one vavle opens) and P(at least one valve fails to open).
The probability that all valves fails is $(0.05)^5$.
The complement of that is the probability that at least one opens.

$(0.95)^5$ is the probability that all open.