N1

Assume that the BP rig in the Gulf of Mexico has four major safety devices all connected in a series.

The corresponding reliabilities of these four devices are:

Device 1: 0.85

Device 2: 0.95

Device 3: 0.80

Device 4: 0.80

Device 2 has a single backup system with identical reliability.

Device 3 has a single backup system which has two subcomponents (each with reliability of .50) that are connected in a series.

Device 4 is backed up by two backup systems (each with reliability of .75).

What is the likelihood that these safety devices (working together) will prevent another disaster?