Stat 401, section 9.2 Two Sample t Test and Confidence Interval
notes by Tim Pilachowski
In section 9.2, were still comparing two groups, but the situation doesnt pass the large-sample test, that is,
either m 40 or n 40. So, instead of using Z as our test
Stat 401 FINAL EXAM _ December 18, 2004
J .Millson ' v
1. A drug is tested to determine whether it can lower the glucose level of
diabetic rats. Five rats are given the drug, while ve others are used as
controls. The blood glucose levels (in mg/ ml) of th
,v_._._._._~_
BR .Camcc. Vang
STAT 401, Final Examination
May 20, 2003, Tu
Full credit will not be given to a problem if you only give the correct
answer without showing derivation.
1.(25%) The data in the following table represent the number of hours o
M
Ws .8qu U
Stat 401 Final Exam Fall 2006
Calculators allowed. All work must be shown to receive ll] credit.
1. Each of a group of 20 intermediate tennis players is given two tennis rackets, one with
gut strings and the other with nylon, each player will
'Stat 401 FINAL EXAM December 19, 2007
J .Millson.
1. A drug is tested to determine whether it can lower the glucose level of g _ '4 u H
diabetic rats. Five rats are given the drug, While 've others'are'fus'ed'as
controls. The blood glucose levels (in mg
STAT 401 FINAL EXAM
H. Glaz ; 13 May 2010
General Instructions: Each problem must be worked on a separate answer sheet; use the back
before requesting a new sheet.
All Problems:
(A) oz = 0.05 unless otherwise stated.
(B) Your answers must include a senten
(:3 CW
STAT 401 FINAL EXAM
H. Glaz ; 18 December 2009
General Instructions: Each problem must be worked on a separate answer sheet; use the back
before requesting a new sheet.
All Problems:
(A) a 2 0.05 unless otherwise stated.
(B) Your answers must inclu
Stat 401 Final Exam Fall 2008
All work must be shown to receive full credit.
1. (30 pts) A sample of 12 radon detectors of a certain type was selected, and each was
exposed to 100 pCi/L of radon. The resulting readings were as follows:
104.3 89.6 89.9 95.
STAT 401 Final Exam 1a (Spring 2008)
Name: Section:
Instructions: You are responsible for showing all the necessary alge
braic work in this exam. Any conclusions unsupported by calculations
will not be credited.
1.(30) A group of four iid observations (de
i 0n ALA;
Stat 401 FINAL EXAM Dec. 21, 2005
J .Millson
1. Suppose that a sample 51:1,m2, - - - ,xg of specimens of ore is collected from
a certain location in a copper mine, and the amount of copper in each of the
specimens is measured in grams. We shall
Stat 401 FINAL EXAM May 17, 2002
J .Millson
1. Suppose that a sample 1:], $2, - - - ,xg of specimens of ore is collected from
a certain location in a copper mine, and the amount of copper in each of the
specimens is measured in grams. We shall suppose tha
Stat 401 Statistics and Probability
Minitab Project 2 Answer Key
I.a. A. Minitab session window
One-Sample Z: C1
Test of = 30 vs < 30
The assumed standard deviation = 12.2647
Variable
C1
N
52
Mean
28.76
StDev
12.26
SE Mean
1.70
95% Upper Bound
31.56
Z
-0.
Stat 401 Hand-in Homework 1 solutions
Part 1. CLT Homework Exercises
A. solutions summary (answers only)
These answers were calculated using exact values and the exact value answers are given. Decimal
approximations are given in part B below. If you used
Sun/T
Name: Signature:
STAT 401 Final Exam, 1:30-3:30pm December 19
o This exam is closed book, but two double-sided formula sheets are allowed.
0 There are 5 problems in all (two pages). Answer all questions in the booklet.
Problem 1. (10+5+10 points)
3:.
Dec. 20, 2014 Stat 401. Final Exam ,
Instructions: Work each numbered problem on a separate answer sheet. (You may use both front and back of each sheet.) Show all
work; partial credit may be given for wrong answers if the method shown is essentially
Cremma I C,
Stat 401 Final Exam Spring 2014
Calculators allowed. All work must be shown to receive zll credit.
1. Each of a group of 25 intermediate tennis players is given two tennis rackets, one with
gut and the other with nylon strings, each player wil
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Stat401
Final exam
M.Jakobson
Show all work, justify your answers.
1.
2.
3.
4.
I
Consider a random variable X and suppose E(X) = 1.1., V(X) = a2.
9.) Find E(X2).
b) Suppose X1,X2, . . . ,Xn is a random sample from population X,
and X i
April 23, 2015
Stat 401 EXAM 2
(chapters 10, 12)
[Pilachowski]
Follow directions carefully:
Counting front and back as one page, number the pages in your answer booklet 1 through 8.
Answer question 1 on answer page 1, question 2 on answer page 2, etc.
Y
March 12, 2015 Stat 401 EXAM 1
(chapters 7 9)
[Pilachowski]
Follow directions carefully:
Counting front and back as one page, number the pages in your answer booklet 1 through 8.
Answer question 1 on answer page 1, question 2 on answer page 2, etc.
You
Final Exam, Stat 401-0201, Spring 2010
You are allowed to use four pages of notes and a calculator.
There are 200 points possible.
1. [30 points] Random samples of students from the University of Prose
and the University of Politics were polled on preferr
Exam 1Stat 401BoyleSpring 2010
You are allowed to use one page of notes and a calculator.
1. [20 points] Suppose X and Y are random variables with expectation
(mean) and variance given as E (X ) = 3, V (X ) = 5, E (Y ) = 2, V (Y ) = 9.
Compute the quantit
Exam 2Stat 401BoyleSpring 2010
You are allowed to use two pages of notes and a calculator.
1. [30 points] Suppose you are given 15 pairs of numbers,
(x1 , y1 ), (x2 , y2 ), . . . , (x15 , y15 )
and the summary statistics
xi = 40
(xi )2 = 1, 000
yi = 90
(y
Exam 1Stat 401BoyleSpring 2010
SOLUTIONS
You are allowed to use one page of notes and a calculator.
1. [20 points] Suppose X and Y are random variables with expectation
(mean) and variance given as E (X ) = 3, V (X ) = 5, E (Y ) = 2, V (Y ) = 9.
Compute t
Exam 1Stat 401BoyleSpring 2010
You are allowed to use one page of notes and a calculator.
1. [20 points] Suppose X and Y are random variables with expectation
(mean) and variance given as E (X ) = 3, V (X ) = 5, E (Y ) = 2, V (Y ) = 9.
Compute the quantit
STAT 401, Homework 2 (double sided)
NAME:
1. Suppose we have a Poisson distribution:
e m
,
m!
P (X = m) =
m = 0, 1, 2, .
Poisson distribution can be used to model the number of customers visiting a
store. For example, within the next hour, the probability
STAT 401, Homework 6 (single sided), Due May 1, Wed
NAME:
A company (called Toluca) wishes to determine the relationship between the
size of a production (X) and the labor hours (Y) required to produce it. There are
n=25 samples randomly collected. The si
STAT 401, Homework 1 (double sided)
NAME:
1. (Ex 15 Page 255 of Devore 8th ed) Let X1 .Xn represent an iid sample from a
Rayleigh distribution with density
x x2 /(2)
e
,x > 0
f (x; ) =
It can be shown that EX 2 = 2
P
1) find an unbiased estimator of using
STAT 401, Homework 3 (double sided)
NAME:
The following data represent a sample of the assets (in millions of dollars) of 5
credit unions in southwestern Pennsylvania. We do not know the true variance, but
we do know the assets are normally distributed.
1
STAT 401, Homework 4
NAME:
1. Certain lightbulbs are advertised as having an average lifetime of 750 hours.
A faculty member has decided to go ahead with a purchase arrangement for
her college unless it can be conclusively demonstrated that the true avera