During a Professor's Office Hours,students Arrive,on Average,every Ten Minutes

question 186

Multiple Choice

During a professor's office hours,students arrive,on average,every ten minutes.Assume that the distribution of the time between arrivals follows an exponential distribution.Suppose that a student has just left. What is the probability that the professor has more than 20 minutes before the next student shows up?

• A)0.8187
• B)0.8647
• C)0.1353
• D)0.1813