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151PMT1.pdf

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Department
Statistics
Course
STAT151
Professor
Gregory Wagner
Semester
Winter

Description
Stat 151 Practice Midterm 1 LAST NAME: ___________________ FIRST NAME: ___________________________ STUDENT ID: _________________________________ Instructions: 1) Personal items must be placed on the floor prior to the start of the exam. 2) Everyone must turn off their cell phones, pagers, and all other portable electronic devices. 3) No communications with other students are allowed. 4) Make sure you put your last name (the same one that is illustrated on your One Card), first name (the same one that is illustrated on your One Card), student ID #, and signature on the front page of the exam booklet. 5) This is a closed book exam. You may use the STAT 151 formula sheet and Z­ table provided, and a non­programmable calculator. 6) The exam consists of 25 multiple choice questions worth 1 mark each. 7) Mark all answers on the Scantron sheet by shading in the letter A, B, C, D, or E corresponding to your chosen answer. Make sure your answers are clearly marked by pencils. Otherwise, no marks will be given. 8) Choose exactly one answer for each question. 9) Your score will be based on the number of questions you answer correctly. 10) There are no penalties for incorrect answers. 11) No credit will be given for omitted answers 12) No credit will be given for anything written in the examination booklet. 13) If you change an answer on the Scantron sheet, be sure that you erase your first mark completely; then shade in the circle of the answer choice you prefer. 14) You must mark all your answers on the answer sheet during the allotted time. No additional time will be allowed at the end of the session for this purpose. 15) You must return your Scantron sheet, the exam booklet, the Z­Table and the formula sheet to the instructor when you finish the exam. 16) Copying questions or answers on paper to take from the exam room is prohibited. 17) You have 90 minutes to complete the exam. SIGNATURE: _________________________________ 1 Stat 151 Practice Midterm 1 1. Which is true of the data shown in the histogram? I. The distribution is approximately symmetric. II. The mean and median are approximately equal. III. The median and IQR to summarize these data summarize the data better than the mean and standard deviation. A) I only B) III only C) I and II D) I and III E) I, II, and III Answer: C 2. Two sections of a class took the same quiz. Section A had 15 students who had a mean score of 80, and Section B had 20 students who had a mean score of 90. Overall, what was the mean score for all of the students on the quiz? A) 84.3 B) 85.0 C) 85.7 D) none of these E) It cannot be determined. Answer: C 3. Suppose that a Normal model described student scores in a history class. Parker has a standardized score (z-score) of +2.5. This means that Parker A) is 2.5 points above average for the class. B) is 2.5 standard deviations above average for the class. C) has a standard deviation of 2.5. D) has a score that is 2.5 times the average for the class. E) None of the above. Answer: B 2 Stat 151 Practice Midterm 1 4. The five-number summary of credit hours for 24 students in an introductory statistics class is: Min Q1 Median Q3 Max 13.0 15.0 16.5 18.0 22.0 From this information, we know that A) there are no outliers in the data. B) there is at least one low outlier in the data. C) there is at least one high outlier in the data. D) there are both low and high outliers in the data. E) None of the above. Answer: A 5. A machine that fills cans with soda fills according to a Normal model with mean 12.1 ounces and standard deviation 0.05 ounces. If the cans claim to have 12 ounces of soda each, what percent of cans are underfilled? A) 0 B) 2 C) 2.28 D) 97.72 E) 100 Answer: C 6. Refer to the previous question, if management wants to ensure that only 1% of cans are under- filled and wants the standard deviation remains at 0.05 ounces, what mean does the filling machine need to have to achieve this goal? A) 2.33 B) 11.88 C) 12.12 D) 14.33 E) None of the above Answer: C 7. All but one of the statements below contain a mistake. Which one could be true? A) The correlation between height and weight is 0.568 inches per pound. B) The correlation between height and weight is 0.568. C) The correlation between the breed of a dog and its weight is 0.435. D) The correlation between gender and age is -0.171. E) If the correlation between blood alcohol level and reaction time is 0.73, then the correlation between reaction time and blood alcohol level is -0.73. Answer: B 3 Stat 151 Practice Midterm 1 8. A correlation of zero between two quantitative variables means that A) we have done something wrong in our calculation of r. B) there is no association between the two variables. C) there is no linear association between the two variables. D) re-expressing the data will guarantee a linear association between the two variables. E) None of the above. Answer: C 9. According to The World Almanac and Book of Facts 2004, the debt per capita for the years 1990-2001 gives the following scatterplot: Regression output gives the equation of the regression line as predicted �Debt per capita �����2,231,226 �1128× �Debt Year ��with R = 98.8%. � What is the correlation coefficient r? A) 0.994 B) -0.994 C) 0.988 D) -0.988 E) cannot be determined Answer: A 4 Stat 151 Practice Midterm 1 10. Refer to the previous question, you decide to take a look at a residuals plot before making any predictions. Based on the following residuals plot, does linear regression seem appropriate for these data? A) Yes, because there is a definite curve in the residual plot. B) Yes, because the pattern in the residual plot is not important as long as the original scatterplot shows a linear pattern. C) No, because there is a definite curve in the residual plot. D) No, because the residual plot must reveal a linear line in order for linear regression to be appropriate. E) None of the above Answer: C 11. A philosophy professor has found a correlation of 0.80 between the number of hours students study for his exams and their exam performance. During the time he collected the data, students studied an average of 10 hours with a standard devia
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