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Introduction to Statistics - Midterm Exam 2007 | STOR 155, Exams of Statistics

Material Type: Exam; Professor: Marron; Class: Introduction to Statistics; Subject: STATISTICS AND OPERATIONS RESEARCH; University: University of North Carolina - Chapel Hill; Term: Spring 2007;

Typology: Exams

Pre 2010

Uploaded on 03/16/2009

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Statistics - OR 155, Section 2, Midterm I
Tuesday, February 27, 2007
Name: _______________________________________________________
Pledge: I have neither given nor received aid on this examination.
Signature: _____________________________________________________
Instructions: Do not do any actual numerical calculations (e.g. answers in a form that you would
type into an Excel field, with a working answer, are expected).
1. [16] A survey of a large college class asked the following questions. The results for
each are summarized in the histograms below. Match each question with it histogram.
a. How many minutes do you study on a typical weeknight?
b. Are you right or left handed (right = 0, left = 1)?
c. What is your height in inches?
d. Are you male or female (male = 0, female = 1).
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Statistics - OR 155, Section 2, Midterm I Tuesday, February 27, 2007 Name: _______________________________________________________ Pledge: I have neither given nor received aid on this examination. Signature: _____________________________________________________ Instructions: Do not do any actual numerical calculations (e.g. answers in a form that you would type into an Excel field, with a working answer, are expected).

  1. [16] A survey of a large college class asked the following questions. The results for each are summarized in the histograms below. Match each question with it histogram. a. How many minutes do you study on a typical weeknight? b. Are you right or left handed (right = 0, left = 1)? c. What is your height in inches? d. Are you male or female (male = 0, female = 1).
  1. [20] Motor vehicles for sale are classified as either cars or light trucks, and are also classified as either imported or domestic. The proportion of cars is 30%, while the overall proportion of imported vehicles is 20%, and 6% were imported cars. a. Find the probability that a randomly chosen vehicle is a light truck. b. Find the probability that a randomly chosen vehicle is a car or is imported. c. Find the probability that a randomly chosen vehicle is neither a light truck, nor domestic. d. Find the probability that a randomly chosen vehicle is a domestic light truck. e. If a randomly chosen vehicle is known to be domestic, then find the probability that it is a light truck.
  1. [20] The mean height of women is about 1.4 m, with a standard deviation of 0.08 m. The mean height of men is about 1.6 m, with a standard deviation of 0.1 m. Suppose the correlation of the heights of husbands and wives is 0.25. a. What is the slope of the regression line of the wife’s height on the husband’s height? b. Assuming the answer to (a) is in the Excel cell T23, what is the intercept of the regression line of the wife’s height on the husband’s height? c. Suppose the numerical answer to part (a) is 0.2, and the numerical answer to part (b) is 1.08. Then, what is the equation of the regression line of the wife’s height on the husband’s height? d. Predict the height of the wife of a man who is 1.8 m tall. e. Use the 68-95-99.7 rule to approximate the probability that a randomly chosen husband will be between 1.3 and 1.9 m in height.
  1. [20] Choose a young adult at random. The probability is 0.10 that the person did not complete high school, 0.20 that the person has a high school diploma, but no further education, and 0.40 that the person has at least a bachelor’s degree. a. What must be the probability that a randomly chosen young adult has some education beyond high school, but does not have a bachelor’s degree? b. What is the probability that a randomly chosen young adult completed high school. c. What is the probability that a randomly chosen young adult has no education beyond high school? d. What is the probability that a randomly chosen young adult either did not finish high school, or else has at least a bachelor’s degree. e. What is the probability that a randomly chosen young adult, who has finished high school, has a bachelor’s degree?