Let's see the improvements.
Here, both alarms have to fail
for the "alarms fails to ring" event to happen.
We are going to see that we have other complexities.
Based in that if both alarms depend, for example,
on your home electrical power,
a power outage will make this redundancy irrelevant
because both will fail.
Also, if you set one wrong or forget to set it,
the likelihood of setting the other wrong is affected.
So, to calculate, we have that the probabilities
for each of the clocks are the same.
But they are going to go to an "AND" gate.
That means that both clocks have to fail
to have a failure.
This reduces the probability to 0.012
for all the five different probable failures
or set of failures that we have here at the top right.
So, with this 0.012 frequency,
we can add it to our event tree, or failure event tree,
and it is easy to calculate that the career damage frequency
is now approximately five days late for work per year.
And each individual frequency
is now 2.5 and 2.4.
To summarize, with just one alarm clock,
we will have approximately eight and a half late days per year.
With two alarm clocks, we are not going to have
a very visible improvement in the first scenario.
But we are going to have major impact in the second one.
The results can help you to minimize the risk of being late.
They are going to show you where the risk is coming from
and which are the consequences of that risk.
And it may need more that one improvement to reduce
the overall core damage frequency to an acceptable level.