The Functioning of a Particular Machine Is Dependent on Two

Multiple Choice

The functioning of a particular machine is dependent on two safety valves: A and B. In order for the machine to operate perfectly BOTH valves must function well. Valve A has a 10% chance of failure while valve B has a 5% chance of failure. If you are in charge of maintaining this machine, then you can say that there is at worst a _____ chance of this machine breaking down and so with _____ chance the machine will work fine.

A) 10%; 90%
B) 15.5%; 84.5%
C) 1%; 99%.
D) 90%; 10%.