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Material Type: Exam; Professor: Dupree; Class: Applied Probability & Stats.; Subject: Mathematics; University: Athens State University; Term: Fall 2009;
Typology: Exams
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Modified True-False Determine whether each of the following statements is a true statement or a false statement. If it is false, change the underlined word to make it true. (2 points each) ________1. The relative frequency for a particular category is the number of times the category appears in the data. False-normal frequency ________2. Bar charts and pie charts are graphical methods that are often used in summarizing categorical data. True ________3. Dotplots and stem-and-leaf plots work best for small numerical data sets. True ________4. Numerical Variables are also known as qualitative values. False-quantitative ________5. The number of speeding tickets each student in AP Statistics has received is a numerical variable. True ________6. The three types of central tendencies are Mean, Median, and Variance. False-Mean, Median, and Mode ________7. If the upper tail of the histogram is shorter than the lower tail of the histogram, then the histogram is said to be skewed right. False-left ________8. A histogram with two peaks is said to be bimodal. True ________9. The serial number of an IPOD is a numerical variable. False-categorical ________10. An observational study can result in data that provides evidence for a cause- and-effect relationship. False-experiment ________11. A data set is continuous if the values are isolated points on the number line. False-discrete ________12. Statistical methods, used appropriately, allow us to draw conclusions based on data. True ________13. The ONLY way to show cause & effect is with a well-designed, well-controlled observation. False-experiment ________14. The population mean is denoted by. False- ________15. The population mean is the average of al x values in the entire population. True ________16. The median is nonresistant to the outliers in a data set.
False-resistant ________17. In a sample of size 25 , the median is the average of the 12th^ and 13th values. False- ________18. (^) s^2 is called the sample standard deviation. False-Variance ________19. A trimmed mean is resistant to the outliers in a data set. True ________20. For a data set having a negatively skewed unimodal histogram, the median is larger than the mean. True ________21. When using a 20% trimmed mean, the largest 10% and the smallest 10% of the observations are discarded while computing the mean. False-20% 20% ________22. A z score tells how many standard deviations a value is from the mean. True ________23. The Empirical Rule can only be used when the histogram of the data set can be closely approximated. True Multiple Choice (1 pt each) ________24. Which of the following graphical methods cannot be used on a categorical data set? a. A bar chart. b. A pie chart. c. A stem-and-leaf display d. All of the above methods can be used on a categorical data set. ________25. Which of the following variables yields data that would be suitable for use in a histogram? a. Color of hair b. Brand of stereo c. Gender of an individual d. The time between two consecutive phone calls ________26. Which of the following is a reason to study statistics? a. Being an informed consumer b. Evaluating decisions that affect your life c. Understanding and making decisions d. All of the above are reasons to study statistics. ________27. Which of the following is not a type of sampling bias? a. Cluster b. Under-coverage c. Nonresponse d. Response ________28. A central concern in an observational study is: a. Obtaining a sample at minimum expense b. Obtaining a large sample
c. Roughly 95% of the observations are within three standard deviations of the mean d. Roughly 95% of the observations are within four standard deviations of the mean. Short Answer / Computational Problems: (with possible point values)
c. Draw and label a Frequency Histogram (2 pts)
Sarah, Ned, Sally, Rebecca, Lane
c. If the smallest value was 4.1 rather than 5.2, how would the sample mean and sample median change? ( DO NOT RECALCULATE—Explain) (1 pt) The sample median would not change because it is resistant to outliers. The sample mean would get smaller.
a. Determine the lower quartile, sample median, and upper quartile from the boxplot. Lower quartile=75 upper quartile=90 sample median= b. Determine the sample Interquartile range from the boxplot. IQR=90-75= c. Describe the general shape of the distribution of speed suggested by this boxplot. Skewed to the right d. Would a speed of 100 be considered an outlier based upon the information in the above boxplot? no