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STAT 350 Practice Exam 2 Name (Print), Lecture notes of Ecology and Environment

Johns Hopkins University (JHU)Ecology and Environment

Instructions: 1. Please write you name on every page. 2. You are expected to uphold the honor code of Purdue University. It is your.

Typology: Lecture notes

2022/2023

Uploaded on 05/11/2023

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STAT 350 Practice Exam 2
Name (Print): _______________________________
Instructor (circle one): Ayu Findsen Sellke Troisi
Class Time: 9:30 AM 11:30 AM 12:30 PM
1:30 PM 2:30 PM 3:30 PM ONLINE
Instructions:
1. Please write you name on every page.
2. You are expected to uphold the honor code of Purdue University. It is your
responsibility to keep your work covered at all times. Anyone cheating on the exam will
automatically fail the course, and will be reported to the Office of Dean of Students.
3. Please alert proctors if you observe any cheating during the exam. We highly
appreciate it.
4. It is strictly prohibited to smuggle this exam outside. Your exam will be returned to you
after it is graded.
5. You may have one double-sided 8.5 in x 11 in crib sheet to take this test. The crib
sheet can be handwritten or typed.
6. The only materials that you are allowed are your calculator, writing utensils and
erasers and your crib sheet. If you bring any other papers in to the exam, you will get
a zero on the exam. We will provide scratch paper if you need more room.
7. Leave all your belongings except those permitted for the exam in the front of the room.
We are not responsible for any loss.
8. If you share your calculator or use a cell phone, you will get a zero on the exam.
9. Breaks (including bathroom breaks) during the exam are not allowed. If you leave the
exam room, you must turn in your exam and you will not be allowed to come back.
10. You must show ALL your work to obtain full credit. An answer without showing any
work may result in zero credit.
11. All numeric answers should have two decimal places except answers from the z-table
should have four decimal places.
12. If your work is not readable, it will be marked wrong.
13. After you complete the exam, please turn in your crib sheet, tables and any scrap
paper along with the exam. Do not staple. Please show your Purdue picture ID.
Your exam is not valid without your signature below.
STUDENT: I attest here that I have followed the instructions above honestly while taking this
test and that work submitted is my own, produced without assistance from books, other
people, notes other than my own crib sheets, or other aids.
Signature of Student: __________________________________________
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Partial preview of the text

Download STAT 350 Practice Exam 2 Name (Print) and more Lecture notes Ecology and Environment in PDF only on Docsity!

STAT 350 Practice Exam 2

Name (Print): _______________________________

Instructor (circle one): Ayu Findsen Sellke Troisi

Class Time: 9:30 AM 11:30 AM 12:30 PM

1:30 PM 2:30 PM 3:30 PM ONLINE

Instructions:

  1. Please write you name on every page.
  2. You are expected to uphold the honor code of Purdue University. It is your responsibility to keep your work covered at all times. Anyone cheating on the exam will automatically fail the course, and will be reported to the Office of Dean of Students.
  3. Please alert proctors if you observe any cheating during the exam. We highly appreciate it.
  4. It is strictly prohibited to smuggle this exam outside. Your exam will be returned to you after it is graded.
  5. You may have one double-sided 8.5 in x 11 in crib sheet to take this test. The crib sheet can be handwritten or typed.
  6. The only materials that you are allowed are your calculator, writing utensils and erasers and your crib sheet. If you bring any other papers in to the exam, you will get a zero on the exam. We will provide scratch paper if you need more room.
  7. Leave all your belongings except those permitted for the exam in the front of the room. We are not responsible for any loss.
  8. If you share your calculator or use a cell phone, you will get a zero on the exam.
  9. Breaks (including bathroom breaks) during the exam are not allowed. If you leave the exam room, you must turn in your exam and you will not be allowed to come back.
  10. You must show ALL your work to obtain full credit. An answer without showing any work may result in zero credit.
  11. All numeric answers should have two decimal places except answers from the z-table should have four decimal places.
  12. If your work is not readable, it will be marked wrong.
  13. After you complete the exam, please turn in your crib sheet, tables and any scrap paper along with the exam. Do not staple. Please show your Purdue picture ID.

Your exam is not valid without your signature below.

STUDENT: I attest here that I have followed the instructions above honestly while taking this test and that work submitted is my own, produced without assistance from books, other people, notes other than my own crib sheets, or other aids.

Signature of Student: __________________________________________

Points Earned

Problem 1 (30 points)

Problem 2 (15 points)

Problem 3 (20 points)

Problem 4 (25 points)

Problem 5 (10 points)

Problem 6 (10 points)

TOTAL (105 / 100)

2. (15 points) An environmental group conducted a study to determine whether crows in a certain region were ingesting food containing unhealthy levels of lead. The lead levels of 49

crows in the region were measured and recorded. The mean lead level of the 49 crows in the sample was 4.90 ppm, and the population standard deviation is 0.7 ppm. Carry out a

two-sided test of significance that the true mean is 5.2 ppm, with a significance level 0.01. Make sure you follow the four-step procedure.

3. (20 points) The College of Science at Purdue University is interested in determining how

much time students in that college spend on homework each week. The table below shows

the mean and the standard deviation of the amount of times spent each week (in minutes) for

a random sample of 20 students in Computer Science and a separate random sample of 20

students in Statistics. The college would like to estimate the difference in mean times spent

on homework for all CS and versus all STAT students.

Sample Size Sample Mean Sample Standard Deviation

Computer Science Students

Statistics Students

Difference (CS - STAT) 20 118 75 a) (5 points) Should you use the two sample T or the matched pairs T procedure to analyze the data? Explain your answer. (Stating that you do not have the data to do one of the methods will be counted wrong.)

b) (3 points) Degree of Freedom: If using the matched pairs T, DF = _____________ (fill-in the blank) If using two sample T procedure, DF = 37.38 from software approximation;

c) (12 points) Construct a 95% confidence interval. Be sure to interpret your interval.

4. (cont’d)

(e) (10 points) Carry out a significance test to compare the mean birth weights for the three

countries at a significance level 0.05. Please follow the four step procedure and make a conclusion in context.

5. (10 points) A researcher wants to conduct a study to test whether listening to soothing music for 20 minutes helps to reduce diastolic blood pressure in patients with high blood

pressure, compared to simply sitting quietly in a noise-free environment for 20 minutes. One hundred patients with high blood pressure at a large medical clinic are available to participate

in this study. The null hypothesis for this study is that there is no difference in the mean reduction of diastolic blood pressure for the two treatments and the alternative hypothesis is

that the mean reduction in diastolic blood pressure is greater for the music treatment. If the null hypothesis is rejected, the clinic will offer this music therapy as a free service to their

patients with high blood pressure. Describe Type I and Type II errors and the consequences of each in the context of this study, and discuss which one you think is more serious.

a) (2 pts) Type I Error Description :

b) (2 pts) Consequence of Type I Error in the context of this study:

c) (2 pts) Type II Error Description:

d) (2 pts) Consequence of Type II Error in the context of this study:

e) (2 pts) Discussion on which type of error is more serious.