STAT 1770 MIDTERM-2

Date: March 19, 2010 Time: 12 30- 14 30 Instructions 1. This is a closed book exam.

Name: _______________ I.D. #: _______________

2. You are permitted to use a non programmable calculator approved by the instructor. 3. There are 31 multiple-choice questions in the part A of this exam. For each question exactly one of four answers provided is correct. For each multiple-choice question, circle one of the letters (a)-(d) corresponding to your chosen answer and record it in the answer sheet. The answers are rounded for calculation questions. Choose the best answer. 4. All answers will be graded right or wrong (no partial credit) in this part. Each single question is worth 1 point. 5. In part B, there are 5 long answer/short answer questions. Give in the answers in the space provided. (Your answers should be corrected to 4 decimal places). 6. There are 11 pages in the exam. 7. The exam is graded out of 62 points.

2

PART A MULTIPLE CHOICE QUESTIONS

(31 Points)

1. Which method of data collection is involved when a researcher counts and records the number of students wearing backpacks on campus in a given day? a. An experiment. b. A survey. c. Direct observation. d. None of these choices. 2. A marketing research firm selects a random sample of adults and asks them a list of questions regarding their beverage preferences. What type of data collection is involved here? a. An experiment. b. A survey. c. Direct observation. d. None of these choices. 3. A researcher conducts a study where she divides subjects into two groups, gives each group a certain treatment, and records their responses. What type of data collection is being used here? a. An experiment. b. Direct observation. c. A survey. d. A census. 4. When the population is divided into mutually exclusive sets, and then a simple random sample is drawn from each set, this is called: a. simple random sampling. b. stratified random sampling. c. cluster sampling. d. selection bias. 5. To give away a door prize, the host of a dinner party put each person's name into a hat, mixed them up, and selected one name. What sampling method was used? a. Simple random sample b. Systematic sample c. Stratified random sample d. Cluster sample 6. The collection of all possible outcomes of an experiment is called: a. a simple event b. a sample space c. a sample d. a population

3

7. If event A and event B cannot occur at the same time, then A and B are said to be a. mutually exclusive b. independent c. collectively exhaustive d. None of these choices. 8. The probability of the intersection of two events A and B is denoted by P(A and B) and is called the: a. marginal probability b. joint probability c. conditional probability of A given B d. conditional probability of B given A 9. If the outcome of event A is not affected by event B, then events A and B are said to be a. mutually exclusive b. independent c. collectively exhaustive d. None of these choices. 10. If A and B are independent events with P(A) = 0.4 and P(B) = 0.6, then P( A and B)= a. 0.76 b. 1.00 c. 0.24 d. 0.20 11. If A and B are independent events with P(A) = 0.2 and P(B) = 0.6, then P( A OR B) a. 0.62 b. 0.12 c. 0.60 d. 0.68 12. If A and B are independent events with P(A) = 0.05 and P(B) = 0.65, then P(A B) = a. 0.05 b. 0.0325 c. 0.65 d. 0.8 13. If A and B are mutually exclusive events with P(A) = 0.3 and P(B) = 0.5, then P( A and B) a. 0.30 b. 0.15 c. 0.00 d. 0.20

4 14. If A and B are mutually exclusive events with P(A) = 0.3 and P(B) = 0.5, then P( A OR B) a. 0.00 b. 0.15 c. 0.8 d. 0.2 15. Events A and B are mutually exclusive with P(A) = 0.3 and P(B) = 0.2. Then, P(Bc) = a. 0.00 b. 0.06 c. 0.7 d. 0.8 16. An experiment consists of four outcomes with P(E1) = 0.2, P(E2) = 0.3, and P(E3) = 0.4. The probability of outcome E4 is a. 0.500 b. 0.024 c. 0.100 d. 0.900 17. If P(A) = 0.58, P(B) = 0.44, and P (A and B) = 0.25, then P( A OR B) = a. 1.02 b. 0.77 c. 0.11 d. 0.39 18. If P(A)...