Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
AP Statistics Review Chapters 26 – 27) MULTIPLE CHOICE Name: __________________________________________ Per: ____ Write the letter corresponding to the best answer in the blank provided. In a study of the performance of a computer printer, the size (in kilobytes) and the printing time (in seconds) for each of 22 small text files were recorded. A regression line was a satisfactory description of the relationship between size and printing time. The results of the regression analysis are shown below. ___1. Variable Size Constant Coefficient 3.47812 11.6559 s = 0.6174 R-squared = 87.5% B) 11.6559 C) 0.3153 D) 11.6559 2.086 0.3153 E) 11.6559 1.725 0.3153 B) 0.9354/60 C) 0.9354 + 20 D) 0.9354 E) more information is needed What is the proportion of observed variation in printing time that can be explained by the linear relationship of size and printing time? B) 0.875 C) 0.3153 D) 0.0001 E) none of these Which of the following does a small value of 2 indicate? A) B) C) D) E) ___ 6. E) 0.875 The correlation between file size (in kilobytes) and printing time (in seconds) for this regression analysis is 0.9354. If we convert the printing times from seconds to minutes (divide by 60) and add 20 kilobytes to each file size, what will be the value of the correlation? A) 0.294 ___ 5. D) 3.47812 Which of the following should be used to compute a 95 percent confidence interval for the slope of the regression line? A) (0.9354/60) + 20 ___ 4. probability <0.0001 <0.0001 R-squared (adjusted) = 86.9% A) 3.47812 2.086 0.294 B) 3.47812 1.96 0.6174 C) 3.47812 1.725 0.294 ___ 3. t-ratio 11.8 37 What is the average change in printing time for every increase of one kilobyte in size of the printer? A) 0.294 ___2. s.e. of Coeff 0.294 0.3153 The observed cell counts are reasonably similar to the expected counts. The differences between the observed and expected cell counts are significantly large. A small probability of observing a statistic at least as large as the one observed given that Ho is true. The probability of correctly rejecting a false null hypothesis None of the above The test statistic (obs exp) 2 has a distribution that is exp A) normal B) uniform C) left-skewed D) bimodal E) right-skewed 7. A biology professor at PU (good ol’ Podunk!) teaches several very large sections of introductory biology (note: her graduate student assistants teach the lab sections). Historically, her grades have been distributed as follows: 15% As 30% Bs 40% Cs 10% Ds 5% Fs A random sample of her grades from last semester has the following distribution: Grade A B C D F Total Proportion of historical grades 0.15 0.30 0.40 0.10 0.05 1.00 Number of observed grades 68 91 58 19 8 244 Test an appropriate hypothesis to decide if the professor’s most recent grade distribution matches the historical distribution. Give statistical evidence to support your conclusion. (hint: in order to do this problem, you should start by calculating the expected number of grades in each letter category) 8. A random sample of 200 students was selected from a large college in the United States. Each selected student was asked to give his or her opinion about the following statement. "The most important quality of a person who aspires to be the President of the United States is a knowledge of foreign affairs." Each response was recorded in one of five categories. The gender of each selected student was noted. The data are summarized in the table below: Strongly Disagree Male 10 Female 20 Response Category Neither Somewhat Somewhat Agree nor Disagree Agree Disagree 15 15 25 25 25 25 Strongly Agree 25 15 Is there sufficient evidence to indicate that the response is dependent on gender? Provide statistical evidence to support your conclusion. 9. A certain brand of bite-sized candies comes in three varieties: smooth, crunchy, and chewy. The manufacturer is interested if preferences for the types of candies differ between three school-age groups: elementary, middle, and high school. Separate random samples of students at the three local schools, one of each age group, are taken, and the data from the samples is compiled in the table below. Variety of Candy Population Elementary Middle High School Creamy 33 21 16 Crispy 14 16 12 Chewy 19 17 32 a) At the 1% level of significance, is there evidence that the proportion of students that prefer each variety of candy differs among the various age groups? b) Based on your conclusion in part (a), which type of error (Type I or Type II) might the candy manufacturer have made? Describe this error in the context of the scenario. 10. A random sample of 11 high school students produced the following results for number of hours of television watched per week and GPA. High school students Scatter Plot 3.8 Scatter Plot 2.6 2.0 5 10 15 20 TV_Hours Coef 3.8 -0.0558 StdDev 2.0426 0.01769 Histogram 1 2.6 25 High school students 3 2 0.4 0.0 -0.4 -0.8 3.2 Predictor Constant Hours High school students 3.0 3.4 pred_GPA T 1.86 -3.154 3.8 P 0.05 0.012 -0.8 -0.4 0.0 0.4 residuals 0.8 s = 0.355 R-sq = 53% a) State the least squares regression equation in context. b) State and interpret the slope in context. c) Are the conditions for inference met? d) Is there evidence of a relationship between the number of hours of TV a high schooler watches and his/her GPA? Test an appropriate hypothesis and state your conclusion in proper context. At this point, assume that all conditions for inference have been met. e) Construct a 95% confidence interval to estimate the slope of the least squares regression line.