SOLUTIONS
MAT 167: Statistics
Test II
Instructor: Anthony Tanbakuchi
Fall 2008
Name:
Computer / Seat Number:
No books, notes, or friends.
Show your work.
You may use the attached
equation sheet, R, and a calculator. No other materials. If you choose to use R,
write what you typed on the test or copy and paste your work into a word
document labeling the question number it corresponds to. When you are done
with the test print out the document. Be sure to save often on a memory stick just
in case. Using any other program or having any other documents open on the
computer will constitute cheating.
You have until the end of class to finish the exam, manage your time wisely.
If something is unclear quietly come up and ask me.
If the question is legitimate I will inform the whole class.
Express all final answers to 3 significant digits. Probabilities should be given as a
decimal number unless a percent is requested. Circle final answers, ambiguous or
multiple answers will not be accepted. Show steps where appropriate.
The exam consists of 18 questions for a total of 70 points on 11 pages.
This Exam is being given under the guidelines of our institution’s
Code of Academic Ethics
. You are expected to respect those guidelines.
Points Earned:
out of 70 total points
Exam Score:

MAT 167: Statistics, Test II
SOLUTIONS p. 1 of 11
Solution:
Fall 2008 results.
>
summary( score )
Min .
1 st
Qu.
Median
Mean 3rd Qu.
Max.
65.71
74.29
78.93
80.24
90.18
92.86
>
par (mfrow = c (1 ,
2))
>
boxplot ( score ,
main = ”Boxplot
of
exam
scores ”)
>
h i s t ( score ,
main = ”Histogram
of
exam
scores ”)
65
70
75
80
85
90
Boxplot of exam scores
Histogram of exam scores
score
Frequency
65
70
75
80
85
90
95
0
1
2
3
4
1. (1 point) Why is it important to use random sampling?
2. For the following statements, determine if the calculation requires the use of a
population
distribution
or a
sampling distribution
.
(a) (1 point) Computing a confidence interval for a mean.
Solution:
Sampling distribution. We need to utilize the distribution of the sample
means.
(b) (1 point) Determining a p-value for a one sample proportion hypothesis test.
Solution:
Sampling distribution. We need to utilize the distribution of the sample
statistic.
(c) (1 point) Calculating the probability than an individual weights more than 100 lbs.
Solution:
Population distribution. We need to utilize the distribution of individual’s
weights (the population).
Instructor: Anthony Tanbakuchi
Points earned:
/ 4 points