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Test 2 Form A with Answer Key | Statistical Methods | STAT 303, Exams of Data Analysis & Statistical Methods

Texas A&M University (A&M)Data Analysis & Statistical Methods

Form A Material Type: Exam; Class: STATISTICAL METHODS; Subject: STATISTICS; University: Texas A&M University; Term: Spring 2007;

Typology: Exams

2019/2020

Uploaded on 11/25/2020

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Name: __________________________
Stat 303: Sections 501-502
Spring 2007
Test 2 - Form A
Instructor: Kristin Lennox
Instructions:
1.) Do not open the exam until instructed to do so. (Meanwhile, read the rest of the
instructions.)
2.) For this exam, you are permitted to use three 8 ½ x 11 sheet of notes. (You may use
both sides.) You are also permitted to use a calculator, as long as it does not have a
QWERTY keyboard.
3.) Write your name on this exam sheet. You will be required to turn your exam sheet in.
Failure to do so may result in a grade of 0 for the exam.
4.) Mark your name, UIN, course and section numbers on your scantron. Also, be SURE
to mark your form on the scantron!
5.) Sign your name on the scantron. With this signature, you agree to follow the Aggie
Honor Code:
“An Aggie does not lie, cheat, or steal or tolerate those who do.”
6.) There are 20 multiple-choice questions, each worth 5 points. Please mark your
answers CLEARLY with a #2 pencil. Multiple marks will be counted wrong.
7.) You have 75 minutes to finish this exam.
pf3
pf4
pf5

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Download Test 2 Form A with Answer Key | Statistical Methods | STAT 303 and more Exams Data Analysis & Statistical Methods in PDF only on Docsity!

Name: __________________________

Stat 303: Sections 501-

Spring 2007

Test 2 - Form A

Instructor: Kristin Lennox

Instructions: 1.) Do not open the exam until instructed to do so. (Meanwhile, read the rest of the instructions.) 2.) For this exam, you are permitted to use three 8 ½ x 11 sheet of notes. (You may use both sides.) You are also permitted to use a calculator, as long as it does not have a QWERTY keyboard. 3.) Write your name on this exam sheet. You will be required to turn your exam sheet in. Failure to do so may result in a grade of 0 for the exam. 4.) Mark your name, UIN, course and section numbers on your scantron. Also, be SURE to mark your form on the scantron! 5.) Sign your name on the scantron. With this signature, you agree to follow the Aggie Honor Code: “An Aggie does not lie, cheat, or steal or tolerate those who do.” 6.) There are 20 multiple-choice questions, each worth 5 points. Please mark your answers CLEARLY with a #2 pencil. Multiple marks will be counted wrong. 7.) You have 75 minutes to finish this exam.

  1. A quality control inspector wishes to determine whether or a manufacturing process for silicon wafers produces less than 10% defective wafers. In order to check, he takes a simple random sample of 20 wafers, and determines the proportion of those that are defective. What is the exact distribution of the number of defective wafers in the sample? a) Uniform b) Normal c) Binomial d) Bernoulli e) We can’t tell without knowing the true proportion of defective wafers.
  2. John and George are about to take a chemistry test. John knows that he has an 80% chance of passing, while George has a 90% chance of passing. John reasons that the probability that at least one of them passes is 170%. Which of the following is true? a) John is incorrect, because the probabilities are not disjoint. b) John is incorrect, because the probabilities are not independent. c) John is incorrect, because you can’t add percents. d) John calculated the probability correctly.
  3. Consider the following discrete distribution: X -1 0 1 2 P(X=x) 0.5 0.2 0.1? What is the mean of this distribution? a) 0 b) 0. c) -0. d) 0. e) We can’t tell.
  4. What is z* (the critical value) for a 20% confidence interval? a) 1. b) 0. c) 1. d) 0. e) 0.
  1. In the 2006 election in Maryland’s 1st^ congressional district, incumbent Wayne Gilchrest received 68.8% of the vote. If you randomly selected 100 people from the district who voted in the last election, what is the probability that more than half voted for Gilchrest? a) 0 b). c). d). e) 1
  2. The mean household income in areas served by a shopping mall is $72,500, with a standard deviation of $1,400. What is the standard deviation of the mean household income of 20 randomly selected households from areas served by shopping malls? a) $70. b) $313. c) $51. d) We can’t tell, since we don’t know if the data are normally distributed.
  3. A lab is asked to determine whether or not the mean concentration of an ingredient in a drug is really 0.86 grams per liter. The standard deviation is known to be 0.0068 grams per liter. Three samples are taken, and the mean concentration is found to be 0.8703. What is the value of the test statistic that should be used in this situation? a) 0. b) 1. c) 2. d) 9.
  4. A marine biologist wishes to test whether or not the presence of boats affects the amount of time dusky dolphins spend hunting. When testing the null hypothesis that the presence of boats does not affect dolphins’ hunting behavior, he finds a p-value of 0.0078. Which of the following is a correct interpretation of this p-value? a) The probability that dusky dolphin hunting behavior is not affected by the presence of boats is 0.0078. b) Assuming that dusky dolphins do change their hunting behavior in the presence of boats, the probability of the researcher getting the test statistic found is 0.0078. c) Assuming that dusky dolphins do not change their hunting behavior in the presence of boats, the probability of getting a test statistic as or more extreme than the one found is 0.0078. d) For the sample the biologist observed, groups of dolphins changed their hunting behavior in the presence of boats .78% of the time.
  1. Let X be distributed N(0,7^2 ), and Y be distributed N(2, 6^2 ). If we take independent samples of size 10 from X and Y, what is the probability that the sum of the means of those samples is larger than 3? a) 0. b) 0. c) 0. d) 0. e) 0.
  2. If X ~ N(1, 3^2 ), what is the probability that 1<X<2.5? a) 0. b) 0. c) 0. d) 0.
  3. If the test scores in a statistics class are normally distributed with a mean of 75 and a standard deviation of 7, what is the 80th^ percentile of test scores? a) 80. b) 80. c) 91. d) 82. e) 84.
  4. Which of the following would increase the rate of type II error for a hypothesis test? a) Increasing α. b) Increasing σ. c) Increasing the sample size. d) None of the above.
  5. A coaching service for the SAT claims that their students perform significantly better than average on the math portion of the SAT than untutored students. From a sample of 100 tutored students, the average SAT math score was 520, and the population standard deviation is known to be 30. What is a 95% confidence interval for the average SAT math score of tutored students? a) (514.1, 525.9) b) (461.2, 578.8) c) (518.0, 521.0) d) (515.1, 524.9)