Answer:
the probability that system’s failure is due to the radio =

Explanation:
From the question given;
Let the mean lifetime of the radio
and the mean lifetime of the speaker

we can re-write both expressions as:
and

Let consider
to be the variables which are independent to the exponentially distributed mean of

∴





replace the values now; we have:





Thus, the probability that system’s failure is due to the radio =
