AP Statistics Test 2

Name ______

Each MC question is worth 2 points. Write the answer (use a capital letter)

1. ______

A distribution of SAT Math scores for 130 students at a suburban high school provided the following statistics: Minimum: 485; Q1: 502; Median: 520; Q3: 544; Maximum: 610; Mean: 535; Standard Deviation: 88. Which of the following statements is true? a. The distribution is skewed to the right and there are no outliers. b. The distribution is skewed to the right and there is at least one outlier. c. The distribution is skewed to the left and there is at least one outlier.. d. The distribution is skewed to the left and 65 students scored better than 520. e. The distribution is skewed to the right and 65 students scored better than 535.

2. ______

The boxplots above compare the television ratings for two competing networks. What conclusion(s) can you draw from the boxplots?

I Network A has more shows than Network B. II. Network A has a greater range of ratings than Network B. III. Network A is higher rated than Network B.

a. I and II only b. II and III only c. I and III only d. I, II, and III e. III only 3. ______

The following histogram displays the scores of 33 students on a 20 point Intro to Statistics quiz. The lowest score, 0, is an outlier. The next lowest score, 2, is not an outlier. 4. ______5. ______

6. ______

What value represents the 97.5 percentile in the graph below (assume normal distribution)? 7. ______8. ______

9. ______10. ______

In a statistics course, a linear regression equation was computed to predict the final exam score based on the score of the first test of the term. The equation was where y is the final exam score and x is the score on the first exam. George scored 80 on the first test. On the final exam George scored 85. What is the residual?

a. -4 b. 4 c. 4.5 d. 5 e. 81

Open Ended: Show ALL work. (each question is worth 4 points)

1. The National Directory of Magazines tracks the number of magazines published in the United States each year. An analysis of data from 1988 to 2007 gives the following computer output. The dates were recorded as years since 1988. Thus, the year 1988 was recorded as year 0. A residual plot (not shown) showed no pattern. a. What is the value of the slope of the least squares regression line? Interpret the slope in the context of the problem.

b. What is the value of the y-intercept of the LSRL? Interpret the value of the y-intercept in the context of the problem.

c. Predict the number of magazines published in the US in 1999.

d. What is the value of the correlation coefficient for the number of magazines published? Interpret this correlation. 2. The heights (in inches) and weights (in pounds) of six male Labrador Retrievers were measures. The height of a dog is measured at the shoulder. A linear regression analysis was done and the residual plot and computer output are given below.

a. Is a line an appropriate model to use for this data? Why?

b. Write the equation of the LSRL. Use variable names in the equation. c. Dakota, a male Labrador, was one of the dogs measured for this study. His height is 23.5 inches. Find Dakota’s predicted weight and Dakota’s actual weight. The residual at that point is 1.5 pounds.

d. Interpret the R-sq value in the context of the problem.

3. a. What is the equation of the LSRL?

b. What is the predicted number of words for a child of 7.5 years of age?

c. Interpret the slope of the regression line in the context of the problem.

d. Would it be appropriate to use the model to predict the number of words a 12-year old would know? EXPLAIN

4. The following table gives the ages in months of a sample of children and their mean height (in inches) at that age. a) Find the correlation coefficient and the least squares regression line.

b) Draw a scatterplot of the data and the LSRL on the plot.

c) Construct a residual plot for the data. d) Based on the residual plot, does the line appear to be a good model for the data?