Q1) Time it takes international telephone operator to place overseas phone call is normally distributed with mean of 45 seconds, and standard deviation of 10 seconds.
a) Determine the probability that my call will go through in less than 1 minute?
b) Determine the probability that will get through in less than 40 seconds?
c) Find out the probability that I will have to wait more than 70 seconds for my call to go through?
Q2) Chemical plant has emergency alarm system. When emergency situation exists, alarm sounds with probability 0.95. When emergency situation doesn't exist, alarm system sounds with probability 0.02. Real emergency situation is rare event with probability 0.004. Given that alarm has just sounded, find out the probability that real emergency situation exists?