Stat 230 midterm2 key - Math 230 Sta 230 Spring 2015 Second...

  • Duke University
  • STAT 230
  • Test Prep
  • jtr22
  • 10
  • 100% (5) 5 out of 5 people found this document helpful

This preview shows page 1 - 3 out of 10 pages.

Math 230 / Sta 230Spring 2015Second Midterm ExamApril 7, 2015Time allowed: 75 minutesPrint Name:Instructions:(a) This is aclosed bookexam. You may bring a two-sided A4 paper of your own notes.(b) Use a calculator when necessary.No cellphones.(c)Show your workon the exam in the space provided (you may use the back of pagesif necessary).(d) Please draw a circle or box around your final answers.(e) Keep in mind that there are5problems, worth 100 points in total.(f) Numerical answers:four significant digitsor fractionsin lowest terms. Nonnu-merical:Simplify!(g) Normal distribution table and PDF table attached.(h) Do not cheat.Good luck!
1.(22pts) A bus stop is served by only two bus lines that operate independently. Onaverage Line A buses arrive every 15 minutes, and Line B buses arrive every 20 minutes.We model the passage times of both bus lines as Poisson processes. Assume that a pas-senger will always take the first bus that arrives at the stop.(a) (4pts) Give the rate parametersλ1andλ2in the two Poisson processes (with the unit“per hour”).
(b) (4pts) If Alice is waiting for Line A and she can only take a Line A bus to her desti-nation, what is the probability that she has to wait for more than 15 minutes?

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture