1. A company responds to 80% of all enquiries within 2 working days. The firm received 8 enquiries today.What is the probability that all the 8 enquiries are responded within 2 working days?
2. A random sample of 25 with a mean of 80 and a standard deviation of 30 is taken from a population of 1000 that is normally distributed. The 90% confidence interval is
3. X is normally distributed with a mean of 100 and standard deviation of 5. If Pr (Xa) = 0.0062, what is the value of a
4. X is normally distributed with a mean of 100 and standard deviation of 5. What is the probability that an event is less than 110?
5. Suppose that past history shows that 20% of Sydney trains are late. A sample of 12 trains is selected for an experiment. The probability that at most 4 trains is late is