1) Which of the following situations is the only one which is an example of inferential statistics (as opposed to descriptive statistics)? a) A gym teacher records the average time it takes for all his students to run a mile. b) A retired tennis player calculates that she has won 73% of her matches during her career. c) A driver calculates his mpg (miles per gallon) on sixteen randomly chosen days to estimate his car's true mpg. d) The city treasurer determines that the average tax return in his city last year was $240. e) The principal of a school calculates the average teacher salary at his school to be $42,100 per year. 2) Jason is buying a new laptop. He is comparing different models based on certain variables. Which of the following sets of variables are all numerical (quantitative)? a) The screen size, The manufacturer, The speed of the processor b) The weight of the laptop, The cost of the laptop, The length of the warranty c) The color of the laptop, The type of operating system it uses, The laptop's thickness d) The battery life, The number of positive reviews it has received, Where it is manufactured 3) Which of the following numerical variables is the only one which CANNOT be treated as continuous? ) The temperature in a refrigerator b) The ceiling height of a kitchen ) The water capacity of a bathtub d) The floor area of a bedroom e) Choices (a) - (d) can all be treated as continuous 4) Nationally, 29% of patients admitted to a hospital emergency room do not have health insurance. A survey was conducted of 40 randomly chosen emergency room patients to determine whether they had health insurance. Among the 40 surveyed, 26% said they did not have any health insurance. Which choice(s) below can be labeled a parameter? a) 29% b) 40 c) 26% d) both percentages e) none of these is a parameter 5) Which of the following statements is the only one that is FALSE? a) A standardized score is one that has been converted to standard deviations. b) A discrete variable is one that can be measured in units as small as we choose. c) The standard deviation is the yardstick used to measure statistical distance between data points. d) When there are outliers, the median is often better than the mean as a representation of the "center" of a data set. e) Graphically, the mode of a data set is where the highest point on the distribution occurs. 6) If the graph below is the cumulative line graph for a data set, exactly how many 2's are in the data? 10 a) 0 b) 1 () 2 d) 3 e) 4 f) 6 h) 8 i) cannot be determined with this graph ON7) Twenty-four people were surveyed regarding the number of times they check their email each day. The raw data was recorded as follows: 2, 3, 6, 1, 1, 5, 4, 5, 2, 3, 1, 6, 6, 4, 1, 4, 6, 2, 3, 5, 3, 5, 2, 4 Sketch a histogram of this data on your own paper. The shape of the histogram of this data set is . .... ) normal b) skewed-left c) skewed-right d) uniform e) bi-modal 8) A group of athletes were instructed to consume 200 calories per day more than usual. Which of the following statements is the only one that is TRUE ? a) The group's mean daily caloric intake increased but the median stayed the same. b) The group's mean daily caloric intake stayed the same but the median increased c) The standard deviation of the group's daily caloric intake increased but the mean stayed the same. d) The standard deviation of the group's daily caloric intake stayed the same but the mean increased. e) The mean and standard deviation both increased. 9) Which of the following statements is the only one that is FALSE? ) A parameter is a numerical measure of the entire population. b) Graphically, the mean is the balance point of a distribution. c) A z-score measures a data point's distance (in standard deviations) from the mean. d) In a skewed distribution, the median lies more toward the direction of skew than the mean. 2) The median is the point that splits the data in half (after ordered smallest to largest) 0) The number of days that school is cancelled because of snow is recorded each year for 12 years, and the results are as follows: 2, 1, 3, 3, 1, 1, 2, 3, 6, 2, 4, 2. Find the sample standard deviation of the data. a) 2.091 b) 1.446 c) 1.766 d) 2.301 e) 3.824 1 1) Eight people were randomly sampled as to how many different countries they have visited, with the following results: 2, 4, 1, 3, 6, 2, 1, 3. Find the sample mean, sample median, and sample standard deviation. a) mean: 2.75 median: 4.5 st. dev: 1.669 b) mean: 2.75 median: 4.5 st. dev: 2.786 ) mean: 2.5 median: 4.5 st. dev: 1.669 d) mean: 2.5 median: 4.5 st. dev: 2.786 e) mean: 4.5 median: 2.75 st. dev: 1.669 [ mean: 4.5 median: 2.75 st. dev: 2.786 g) mean: 2.75 median: 2.5 st. dev: 1.669 h) mean: 2.75 median; 2.5 st. dev: 2.786 12) A 200 point test has a mean of 140 and a standard deviation of 12.5. Which of the following is the only statement which MUST be true? a) The mean is the appropriate measure of center for this data. b) A test score of 150 is far above average. ) Half of the students scored below 140. d) A student scores perfect on a make-up test, increasing the mean but not the standard deviation. e) None of statements (a) - (d) have to be true.13) The number of inches of rainfall in Los Angeles is recorded each year for 117 years: MEAN ST DEV 5-number summary 14.94 5.75 4.85, 9.68, 13.07, 19.25, 38.18) Which of the following statements is the only one that is FALSE? a) The distribution of rainfall is skewed left. b) The inter-quartile range is 9.57 c) The standardized maximum rainfall is 3.44. d) 509% of years had a rainfall greater than 13.07. e) At least 759% of years had a rainfall less than 20 inches. 14) Each of the departing airline passengers at a check-in counter produced at most three bags to check-in. 27 passengers had no bags to check in, 36 passengers had one bag to check in, 16 passengers had two bags to check in, and 8 passengers had three bags to check in. What is the mean number of bags checked in for this flight? a) 1.057 b) 1.368 c) 1.500 d) 14.5 e) 21.750 () This mean cannot be determined with the given information. 15) The same exam was given to two small classes, and the means and standard deviations of each were as follows: Class 1: mean - 72, standard deviation = 10.7 Class 2: mean - 75, standard deviation - 11.3 John is in class 1 and scored 60. Sarah is in class 2 and scored 88. Which student - John or Sarah - scored statistically further from their class' mean? a) John was statistically further from his class' mean than Sarah was from her class' mean, b) Sarah was statistically further from her class' mean than John was from his class' mean. c) John and Sarah were the same statistical distance from their respective class' mean, d) This cannot be determined with the given information. 16) Refer to the previous problem. A student in class I had a standardized exam score of 1.7797. What did this student score on her exam? a) 66 b) 69 c) 74 d) 78 e) 82 () 87 2) 91 h) 97 17) Consider the following data set: 71, 34, 114, 89, 75, 19, 90, 87, 68, 108, 101, 76, 119, 93. According to the IQR x 1.5 rule, the following points would be considered outliers: a) 19 b) 34 () 71 d) 93 e) 114 f) 119 2) 19, 34 h) 19, 119 i) 114, 119 j) 19, 34, 119 k) 19, 114, 119 1) 19, 34, 114, 119 m) none of these points are outliers 18) A study was conducted to determine how the level of alcohol intake affects hand-eye coordination. Hand-eye coordination was measured by how long a person could balance an object with one hand. Alcohol intake was found to explain 64% of the variation in hand-eye coordination. In this study, what is the correlation between level of alcohol intake and hand-eye coordination? a) r = 0.64 b) r= -0.64 () r = 0.08 d) r= -0.08 () r = 0.8 () r= -0.8 g) r = 0.41 h) r= -0.4119) The British government conducts regular surveys of household spending. The average weekly household spending on tobacco products and spending (in British pounds) on alcoholic beverages for each of 11 regions in Great Britain were recorded. The data are as follows: alcohol: 2.5 2.8 3.2 3.3 3.4 3.4 3.7 3.7 4.0 4.5 4.6 tobacco: 4.7 4.5 5.9 4.9 5.6 5.2 6.0 61 6.5 6.0 3.9 Which of the following statements is the only one that is TRUE ? a) There are no outliers in this data set. b) Every 1 pound increase in spending on alcohol corresponds to an increase of about 4.50 pounds on tobacco. :) Every 1 pound increase in spending on alcohol corresponds to an increase of about 0.25 pounds on tobacco. d) Spending on alcohol explains about 20% of the variation in spending on tobacco. e) If we measured the spending in dollars instead of pounds, the correlation coefficient would decrease because a dollar is worth less than a British pound. 20) A researcher examines several models for predicting tornados. Below are several models that include variables of interest. Beside each model is its corresponding r-squared. Model 1: temperature, barometric pressure r-squared: 0.11 Model 2: temperature, barometric pressure, wind speed r-squared: 0.33 Model 3: temperature, barometric pressure, wind speed, humidity r-squared: 0.34 Model 4: temperature, barometric pressure, wind speed, humidity, time of year r-squared: 0.51 Model 5: temperature, barometric pressure, wind speed, humidity, time of year, location r-squared: 0.63 Which of the following statements is the only one that is TRUE? a) The preferred model is Model 1 since it has the least number of variables. b) The researcher would likely use Model 3 with one of the variables deleted. c) The r-squared gets bigger each time the researcher adds a variable so all the variables must be important. 1) Time of year is not an important variable for predicting tornados. e) The researcher would likely use Model 5 with one of the variables deleted. 21) The batting averages for Derek Jeter and David Justice in both 1995 and 1996 are shown below: 1995 1996 combined Derek Jeter 0.250 0.314 0.310 David Justice 0.253 0.321 0.270 It appears that David Justice had the higher batting average both years, but a lower average when combined. This phenomenon is known as . . . . a) Simpson's Paradox b) confounding c) common response d) correlation by coincidence e) statistical bias f) sensitivity to outliers g) direct causation h) multiple regression 22) A recent study found that people who donate kidneys tend to lead long healthy lives themselves. Researchers were quick to point out that people who are healthy are more likely to donate a kidney than people who are not, so overall health is an indicator of both longevity and the desire to donate a kidney. These researchers are suggesting that this observation is due to? a) Simpson's Paradox b) confounding c) common response d) correlation by coincidence e) statistical bias f) sensitivity to outliers g) direct causation h) multiple regression