probability question

3. Students arrive at a local bar at a mean rate of 30 students per hour. Assume that the bouncer waits X (minutes) to card the next student. That is, X is the time between two students arriving at the bar. Then we know that X has approximately an exponential distribution. (a) (8 points) What is the probability that nobody shows up within the 2 minutes after the previous customer? (b) (8 points) What is the probability that the next student arrives in the third minute, knowing that nobody has shown up in the 2 minutes since the previous student