MATH26367_Midterm_vB_F2016.docx

MATH 26367 Statistical Methods Fall 2016 MATH 26367 Statistical Methods – Midterm B INSTRUCTOR: Stephane Lemieux DATE : Tuesday, Oct. 18 th , 2016 DURATION : 90 minutes (40 total marks, 25% of the overall course grade) STUDENT NAME: SLATE USER ID: PART 1: Multiple choice questions, circle the best answer. 1 mark each, 5 total. 1. The following table provides information on 2 of the 105 earthquakes that occurred on May 10, 2013. Magnitude was measured using the Richter scale and NST stands for the number of stations that reported the activity of the same earthquake. Time NST Depth (km) Magnitude Region 03:46:54 25 16.7 1.6 N. California 15:19:57 11 7.7 1.8 Tennessee Which column in the table above contains discrete, quantitative data ? a. Time b. NST c. Depth d. Magnitude e. Region 2. Which of the following best describes the skew of the graph below? a. Symmetric b. Positive skew c. Skewed left d. Negative skew Midterm exam Page 1 of 9

MATH 26367 Statistical Methods Fall 2016 3. Which if the following images displays the highest degree of positive correlation? a. b. c. d. e. 4. A computer crashes once every two days on average. What is the most accurate experimental model that you can use to determine the probability of the computer crashing twice in one week? a. Normal b. Binomial c. Poisson d. None of the above 5. The grades for a statistics quiz are normally distributed with a mean grade of 58 and a standard deviation of 8. If a passing grade is 50, apply the empirical rule to calculate how many students passed the quiz if the class has 25 students? a. 13 b. 15 c. 17 d. 19 e. 21 Midterm exam Page 2 of 9

MATH 26367 Statistical Methods Fall 2016 PART 2: Short answer questions, show all your work for full marks. Marks are provided for each question, (35 marks total). 1. 80% of personal computer users have firewalls set to encrypt messages. If 20 users are sampled at random, what is: (5 marks total) a. The expected probability that exactly 18 users have firewall encryption? (2 marks) b. The expected probability that at most 18 users have firewall encryption? (2 marks) c. The expected number of users that have firewall encryption? (1 mark) Midterm exam Page 3 of 9

MATH 26367 Statistical Methods Fall 2016 2. The chief of IT security has asked you to estimate next quarter’s budget based on the following data: (5 marks total) Quarter Months in Operation Budget (in $000’s) Months x Budget Months^2 2015 Q3 3 58 174 9 2015 Q4 6 75 450 36 2016 Q1 9 61 549 81 2016 Q2 12 77 924 144 2016 Q3 15 75 1125 225 2016 Q4 18 80 1440 324 Sum 63 426 4662 819 Average 10.5 71 777 136.5 You decide to do regression using months in operation and budget. a. What is the slope of your regression line? (2 marks) b. What is the intercept of your regression line? (2 marks) c. What is your estimate of next quarter’s (2017 Q1) budget? (1 mark) Midterm exam Page 4 of 9

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help