Question

A room has two light bulbs and one switch. Assume the following:

• The room is windowless.

• The switch can only fail to close.

• The room will only become dark if there is no electricity, both light bulbs burn out,

  or the switch fails to close.

• There will be no electricity either for fuse or power failure.

1. a) Develop a fault tree for the top event —room has no light.

2. b) In developing the fault tree, there are 5 basic fault events. Assume that the probability of occurrences of these fault events (E1, E2, E3 E4, and E5) is 0.04, 0.05, 0.06, 0.07, and 0.08 respectively. Calculate the probability of occurrence of the top event (in %) — room has no light.

Answer 1