CAS Exam MAS-I Fall 2019, Question 2

Study guide: Exam MAS-I

You are given the following information about waiting times at a subway station:

• Subway trains arrive at a Poisson rate of 20 per hour
• 30% of the trains are Express and 70% are Local
• The arrival times of each train are independent
• An Express train gets you to work in 18 minutes, and a Local train gets you there in 30 minutes
• You always take the first train to arrive and you get to the office in X_1 minutes from the time you arrive at the subway station
• Your coworker always takes the first Express train to arrive and he gets to the office in X_2 minutes from the time he arrives at the subway station

Calculate the expected value of X_1 - X_2.

• A) Less than -2.0
• B) At least -2.0, but less than -1.0
• C) At least -1.0, but less than 0.0
• D) At least 0.0, but less than 1.0
• E) At least 1.0

Answer this question and see the worked solution

Concepts tested

• Poisson Process
• Exponential Distribution
• Interarrival Time
• Expected Value
• Poisson Thinning

More questions from this set

• CAS Exam MAS-I Fall 2019, Question 1
• CAS Exam MAS-I Fall 2019, Question 3