While listening to Pinball Wizard, you decide to conduct an experiment in which you play pinball over

Question:

While listening to "Pinball Wizard," you decide to conduct an experiment in which you play pinball over and over again. Each game takes an Exponential amount of time to finish, with expected value of 3 minutes.
a. What is the density of the time that you spend, if you play two games in a row?
b. What is the probability that you will be finished with two games in a total of five minutes or less?