The time between visits to a U.S. emergency room for a member of the general population follows an exponential distribution with a mean of 2.5 years. What proportion of the population:
a. Will visit an emergency room within the next 6 months?
b. Will not visit the ER over the next 6 years?
c. Will visit an ER next year, but not this year?
d. Find the first and third quartiles of this distribution.