Inquiries of the Poisson Portal interactive query system arrive at the central computer in a Poisson pattern at an average rate of 13 inquiries per minute.
a. What is the mean time between successive inquiries?
b. What is the probability that the time interval between the next two
inquiries will be no more than 8 seconds?
c. More than 11 seconds?
d. Between 8 seconds (not included) and 11 seconds (included) seconds?