STAT 420
(due Friday, January 25, by 4:00 p.m.)
Homework #1
Spring 2008
1.
The salary of junior executives in a large retailing firm is normally distributed with standard deviation = $1,500. If a random sample of 25 junior executives yields an
STAT 420
Homework #3
(due Friday, February 8, by 4:00 p.m.)
Spring 2008
1.
An employee claims that drinking beer has no effect on the amount of time it takes for him to perform a particular task. The following data show how many seconds he took t
STAT 420
Examples #18
Fall 2007
The cutting speeds of four types of tools are being compared in an experiment. Five materials of varying degree of hardness are to be used as experimental blocks. Measurements of cutting time (in seconds) according
STAT 420
Homework #3
(due Friday, February 8, by 4:00 p.m.)
Spring 2008
1.
An employee claims that drinking beer has no effect on the amount of time it takes for him to perform a particular task. The following data show how many seconds he took t
STAT 420 Spring 2008 Version B
Name _
Exam 2
Page 1 2 3 4 5 6 Total Possible 16 9 13 8 4 10 60 Earned
Be sure to show all your work; your partial credit might depend on it.
No credit will be given without supporting work.
The exam is closed book
STAT 420
(10 points) (due Friday, March 7, by 4:00 p.m.)
Homework #6
Spring 2008
1.
Can a corporations annual profit be predicted from information about the companys chief executive officer (CEO)? Forbes (May, 1999) presented data on company pro
STAT 420
(10 points) (due Friday, March 14, by 4:00 p.m.)
Homework #7
Spring 2008
1.
A forester seeking information on basic tree dimensions obtains the following measurements of the diameters 4.5 feet above the ground and the heights of 12 suga
Exam 1
1.
(Version A white)
(Answers)
The population of Lilliput is divided into Little-Endians and Big-Endians based on which end of a boiled egg they believe should be opened. Suppose that 60% of Lilliputians are Little-Endians, and 40 % are Bi
STAT 420
Homework #5
(due Friday, February 29, by 4:00 p.m.)
Spring 2008
1.
a)
For the prostate data, fit a model with lpsa as the response and the other variables as predictors. Plot the residuals vs. the fitted values. Check the constant varian
STAT 410
Summer 2009
Homework #2
(due Wednesday, June 24, by 4:00 p.m.)
1.
The time, T, that a manufacturing system is out of operation has cumulative distribution function 2 2 1 if t > 2 t F(t) = 0 otherwise The resulting cost to the company is Y = T 2.
STAT 420
Homework #1
(due Friday, January 25, by 4:00 p.m.)
Spring 2008
1.
The salary of junior executives in a large retailing firm is normally distributed with standard deviation = $1,500. If a random sample of 25 junior executives yields an a
2.2
The dataset uswages is drawn as a sample from the Current Population Survey in 1988. Fit a model with weekly wages as the response and years of education and experience as predictors. Report and give a simple interpretation to the regression coef
STAT 410
Homework #10
(due Friday, July 31, by 4:00 p.m.)
Spring 2009
1.
Suppose X 1 , X 2 , , X n are independent random variables, and X i has Geometric distribution with probability of success p i , i = 1, 2, , n. Let Y = min X i . What is the probabil
STAT 420
1.
Summer 2012
Practice Problems 2
Suppose that the amount of beer a person has consumed ( X ) and the persons
blood alcohol level ( Y ) in a certain bar follow a bivariate normal distribution with
X = 60 oz,
a)
X = 15 oz,
Y = 0.072,
Y = 0.02
STAT 420 Spring 2008 Version A
Name
ANSWERS
.
Exam 2
Page 1 2 3 4 5 6 Total Possible 4 10 13 16 9 8 60 Earned
Be sure to show all your work; your partial credit might depend on it.
No credit will be given without supporting work.
The exam is cl
Exam 1
1.
(Version B yellow)
(Answers)
Suppose the moment-generating function of a random variable X is M X ( t ) = 0 .3 + 0 .6 e 2 t + 0 .1 e 5 t .
a) (3) Find the probability P ( X 3 ).
x
0 2 5
f(x)
0.3 0.6 0.1 P ( X 3 ) = f ( 0 ) + f ( 2
STAT 408 Spring 2009 Version A
Name _
AD1
34
AD2
45
AD3
23
Exam 1
Please circle your discussion section.
Be sure to show all your work; your partial credit might depend on it.
No credit will be given without supporting work.
The exam is closed
STAT 420 Spring 2009 Version A
Name
ANSWERS
.
Exam 2
Page 1 2 3 4 5 6 7 Total Possible 9 9 3 9 9 10 11 60 The exam is closed book and closed notes. You are allowed to use a calculator and one 8" x 11" sheet with notes on it. Earned
Be sure to sh
STAT 420
Spring 2012
Homework #6
1.
In order to determine the profitability of hiring an additional salesman, the sales manager
decided to determine the relationship between the number of salesmen and the average
sales in thousands of dollars.
X ( number
STAT 420
Spring 2012
Name
Section D1
ANSWERS
.
Version B
Exam 2
Page
Points
Be sure to show all your work; your
partial credit might depend on it.
1
No credit will be given
without supporting work.
2
3
Turn in all scratch paper with your exam.
4
( I would
STAT 410
Summer 2009
Homework #2
(due Wednesday, June 24, by 4:00 p.m.)
1.
The time, T, that a manufacturing system is out of operation has cumulative distribution function 2 2 1 if t > 2 t F(t) = 0 otherwise The resulting cost to the company is Y = T 2.
STAT 410
Summer 2009
Homework #1
(due Friday, June 19, by 4:00 p.m.)
1.
Suppose a discrete random variable X has the following probability distribution: P( X = k ) =
( ln 2 ) k
k!
,
k = 1, 2, 3, .
a)
Verify that this is a valid probability distribution.
STAT 420
(10 points) (due Friday, March 28, by 4:00 p.m.)
Homework #8
Spring 2008
1.
a)
For the prostate data, fit a model with lpsa as the response and the other variables as predictors. Implement the Backward Elimination variable selection met
STAT 410
Homework #11
(due Wednesday, August 5, by 4:00 p.m.) Bert and Ernie noticed that the following are satisfied when Cookie Monster eats cookies:
Summer 2009
1 2.
(a)
the number of cookies eaten during non-overlapping time intervals are independent;
STAT 420
Homework #2
(due Friday, February 1, by 4:00 p.m.)
Spring 2008
1.
We would like to test the effect of drugs 1 and 2 on a physiological measure X. Consider the model: X 1 1 , X 1 2 , , X 1 n are i.i.d. N ( 1 , 2 ) X 2 1 , X 2 2 , , X
STAT 420
Homework #5
(due Friday, February 29, by 4:00 p.m.)
Spring 2008
1.
a)
For the prostate data, fit a model with lpsa as the response and the other variables as predictors. Plot the residuals vs. the fitted values. Check the constant varian
STAT 410
Homework #11
(due Wednesday, August 5, by 4:00 p.m.) Bert and Ernie noticed that the following are satisfied when Cookie Monster eats cookies:
Summer 2009
1 2.
(a)
the number of cookies eaten during non-overlapping time intervals are independent;
STAT 420
Homework #4
(due Friday, February 15, by 4:00 p.m.)
Spring 2008
1.
Recall Problems #5 and #6 from Homework 1: It has been proposed that the brightness measured in some unit of color or a commercial product is proportional to the time it
STAT 420
Spring 2012
Homework #8
(due Monday, April 2, by 4:30 p.m.)
1.
Do NOT use a computer for this problem.
The data below describe a random sample of 10 students who recently graduated from
Anytown State University, all majoring in Actuarial Science.
STAT 408
Spring 2009
Homework #1
(due Friday, January 30, by 3:00 p.m.) Suppose that P(A) = 0.40, P(B) = 0.30, P(A B) = 0.20. What is the probability that . a) c) either A occurs or B occurs (or both); B occurs and A does not occur; b) d) a) b) c)
-title: 'STAT 420: Homework 4'
author: "Spring 2017, Unger"
date: 'Due: Tuesday, February 28 by 11:50 PM CT'
output:
html_document:
theme: readable
toc: yes
-# Assignment
# Exercise 1 (Using `lm` and `anova`)
For this exercise we will use the data stored
-title: 'STAT 420: Homework 6'
author: "Spring 2017, Unger"
date: 'Due: Tuesday, March 28 by 11:50 PM CT'
output:
html_document:
theme: readable
toc: yes
-# Assignment
# Exercise 1 (EPA Emissions Data)
For this exercise we will use the data stored in [`ep
-title: 'STAT 420: Homework 3'
author: "Spring 2017, Unger"
date: 'Due: Thursday, February 16 by 11:50 PM CT'
output:
html_document:
theme: readable
toc: yes
-# Assignment
# Exercise 1 (Using `lm` for Inference)
For this exercise we will again use the `fa