Illinois State University Mathematics Department
MAT 312: Probability and Statistics for Middle School Teachers Spring 1999 
Possible Solutions to Quiz #2 look at Quiz #2 look at course grades 


10 Multiple Choice Questions 
1 point each 

Impact on Semester Grade 
approximately 2% to 3% 


Select the letter of the most correct response for each question.
1. The scatter plot to the right shows a _?_ relationship. [Assume that vertical and horizontal axes are identically scaled.]
 a. strong negative
 b. strong positive
 c. weak positive
 d. weak negative
2. A twovariable data set consists of ordered pairs representing age in years and height in inches for 250 undergraduate education majors. A spaghetti line is drawn and its equation determined in order to represent the data set. The equation is then used to predict the height of school children, based on their age, as they enter first grade. This use of the spaghetti line equation is called _?_.
 a. extraordinary
 b. interpolation
 c. elevation
 d. reciprocation
 e. extrapolation
 f. aberration
3. Three fundamental characteristics of a twovariable relationship are _?_.
 a. shape, location, and direction
 b. location, strength, and spread
 c. strength, shape, and direction
 d. shape, spread, and location
4. A linear model relates the number of ice cream cones sold (c) to the profit, in dollars, of an ice cream stand (P). For example, (356, 16.87) represents selling 356 cones and earning a profit of $16.87. If the linear relationship P = 0.37c  114.85 perfectly models this relationship, what is the meaning of the verticalaxis intercept of the linear equation?
 a. When no cones are sold, there is a profit of $114.85.
 b. When no cones are sold, there is a loss of $114.85.
 c. Each cone sold generates $0.37 profit.
 d. Each cone costs $0.37 to produce.
5. Which of the following is the least justifiable criterion for positioning a spaghetti line on a scatter plot to represent the relationship between two variables?
 a. Position the line so that about half the points are above the line and about half the points are below the line.
 b. Position the line to keep the points as close to the line as possible.
 c. Position the line to account for the realworld context.
 d. Position the line so that it passes through the origin.
6. Here is a representation for a linear relationship:
Choose the representation below that captures the same linear relationship.
Correct Response: e.
7. A data set of 125 ordered pairs relates age of a car, in years (a), to the resale value of the car, in dollars (R). For example, (3, 9250) represents a 3yearold car having a resale value of $9250. Suppose that a medianmedian line is calculated for this data set and is represented by the equation R = 1256a + 11952. In this equation, the number 1256 represents _?_.
 a. the value of a car after 3 years
 b. a slope of 1256
 c. the verticalaxis intercept of the line
 d. an increase of $1256 in the value of a car over a oneyear period
 e. a decrease of $1256 in the value of a car over a oneyear period
Review Situations
8. If a onevariable data set consists of numerical scores from a final exam, the data can be considered ratio data if _?_.
 a. there are 100 points possible on the exam
 b. an equal ratio of As, Bs, Cs, Ds, and Fs are assigned
 c. an exam score of 0 represents no points earned
 d. someone who scored 45 on the exam earned half the points of someone who scored 90 on the exam
 e. None of the responses (a) through (d) are appropriate.
 f. More than one of the responses (a) through (d) are appropriate.
9. A data set has a midspread of 40 and a lower quartile (25th percentile) of 185. The lower outer fence is _?_.
 a. 40
 b. 65
 c. 125
 d. 185
 e. 245
 f. 305
10. The mean number of points scored per game for basketball great Sir Charles Barkley is 28.4. If a game total of 20 points is unlikely for Sir Charles, then the standard deviation of his pointspergame data set must be _?_.
 a. at least 4.2 points per game
 b. less than or equal to 5.0 points per game
 c. less than 4.2 points per game
 d. smaller than 2.5 points per game
Administered Thursday 16 February 1999 . 