Respuesta :
Answer:
0.61
Step-by-step explanation:
The computation of the probability of the working of the system is shown below:
But before that first we have to find out the total probability of sub-system i.e 2,3 and 4 i.e
[tex]= 0.75\times0.8\times0.8[/tex]
= 0.48
Now the working of the system probability is
= 1 - [(1 - probability of component 1) × (1 - sub system probability)]
= 1 - [(1 - 0.75) × (1 - 0.48)]
= 1 - 0.39
= 0.61
Please find the attachment for better understanding.

Answer:
0.87
Step-by-step explanation:
First subsystem now working:
1 - 0.75
0.25
Second subsystem not working:
1 - (0.75 × 0.8 × 0.8)
1 - 0.48
0.52
System wouldn't work if both fail
P(working) = 1 - (0.52×0.25)
1 - 0.13
0.87