HW practice/Study Guide

ECO 391-003/005

Fall 2013

Assignment 2 (Revised Version: October 2)

Due: Monday, October 7, 2013 (11:59 PM Eastern Daylight Time)

This assignment will be graded on a 100 point scale (i.e. 90, 80, 70, 60) and will

be worth 4% of your overall course grade. The grade will be weighted

accordingly on Blackboard and in determining your final course grade.

1. According to a 2007 Pew Research Center survey, 38% of the “Millennial”

generation claims to have at least one tattoo. Suppose that you were to

ask 15 UK students if they had a tattoo;

a. What is the probability that none of them have a tattoo? [10 points]

b. What is the probability that at least 10 of them have a tattoo? [10

points]

2. According to the U.S. Travel Association, the average member of

Generation Y (those born after 1980) takes an average of 3.9 leisure trips

via air travel per year.

a. Assuming the number of trips is distributed according to a Poisson

Distribution, how likely is it that a typical Generation Y traveler will fly

for leisure purposes 10 times in a two year period?[10 points]

b. How likely is it that this same typical flier would not fly for leisure

purposes at all over the same period? [5 points]

3. Keeneland is a popular horse racing track outside of Lexington that

happens to have several drive-thru betting windows for people who

would like to place wagers on races without entering the grandstand

area. Suppose the mean time it takes an employee at one of these

betting windows to serve a customer is 87 seconds, and this time is

exponentially distributed.

a. Determine the rate parameter. [10 points]

b. Determine the probability that someone will have to wait more than

120 seconds for the car in front of them to finish. [15 points]

4. Of the over 1.6 million graduating high school students who took the

American College Test (ACT) in 2012, the mean score was 21.1 and the

standard deviation was 5.3. Assuming that the scores are distributed

normally;

a. Find P(X≤30) [3 points]

b. Find P(16≤X≤23) [4 points]

c. Find the score such that P(X>x) = .56 [4 points]

d. Assume that the University of Kentucky will only accept applicants

that scored higher than a 19 on the ACT. What is the probability

that a student taking the exam in 2012 would not qualify for

admission? [4 points]

5. Chapter 7: p. 236, Problem 49 (parts a and b only) [5 points each part]

6. Chapter 8: p. 267, Problem 73 (parts a, b and c) [5 points each part]