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# Statistics in Action Practice Test

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By McGraw-Hill Professional
Updated on Sep 13, 2011

## Statistics in Action Practice Test

You may draw diagrams or use a calculator if necessary. A good score is at least 45 correct.

1. The process that is used to draw conclusions on the basis of data and hypotheses is called
1. the null hypothesis
2. a scenario
3. inference
4. regression
5. correlation
2. Table Test 2-1 shows an example of
1. sampling without replacement
2. sampling in ascending order
3. sampling in descending order
4. sampling of primary elements
5. sampling of means
3. In a normal distribution, the width of the confidence interval is related to
1. the difference between the mean and the mode
2. the difference between the mean and the median
3. the number of modes either side of the standard deviation
4. the number of standard deviations either side of the mean
5. none of the above
4. Suppose an experiment is conducted in which people's average daily caloric intake is plotted to get a distribution. The intent is to get a good representative sampling of the entire population of the United States. Errors in this experiment might arise because of
1. uncertain data on the caloric content of foods
2. sloppy reporting or monitoring of people's food intake
3. a small number of people sampled
4. the gathering of data from cities but not from rural areas
5. any of the above
5. Imagine that the above experiment is conducted, and someone says on the basis of the results, "A typical person in the United States consumes between 2700 and 3300 calories a day." This is the equivalent of saying:
1. "A typical person in the United States has a daily caloric consumption of 3000±10%."
2. "A typical person in the United States has a daily caloric consumption of 3000±3%."
3. "A typical person in the United States has a daily caloric consumption of 3000±1%."
4. "A typical person in the United States has a daily caloric consumption of 3000±0.3%."
5. "A typical person in the United States has a daily caloric consumption of 3000±0.1%."
6. Imagine a town in a southern U.S. city. There is a computer store in this town. The owner of the store believes there is a correlation between the temperature and the number of computers sold per day. She looks back over the past year's sales records and determines the number of computers sold on 12 different days (one in each month of the year). Then she goes to the Internet and finds the average temperatures (high plus low divided by 2) for each day in her town. When she places the resulting points on a scatter plot, she gets Fig. Test 2-1. This suggests
1. that there is no correlation between the average temperature on a given day and the number of computers sold by her store on that day
2. that there is a negative correlation between the average temperature on a given day and the number of computers sold by her store on that day
3. that there is a positive correlation between the average temperature on a given day and the number of computers sold by her store on that day
4. that more information is needed to figure out if there is a correlation between the average temperature on a given day and the number of computers sold by her store on that day
5. no useful information whatsoever
7. The dashed line in Fig. Test 2-1 is an estimate of the
1. line of least squares
2. regression curve
3. correlation ratio
4. standard deviation
5. variance
8. Imagine that the points in a scatter plot are arranged in a perfect circle, evenly spaced all the way around. What is the orientation of the least-squares line?
1. It is horizontal.
2. It is vertical.
3. It ramps up as you move toward the right.
4. It ramps down as you move toward the right.
5. It is impossible to determine because infinitely many different lines can, in theory, be defined as the least-squares line.
9. Imagine that the points in a scatter plot are arranged in a perfect circle, evenly spaced all the way around. What is the correlation between the variables in this case?
1. 0
2. Something between 0 and +1
3. +1
4. Something between –1 and 0
5. –1
10. A hypothesis is always
1. an assumption
2. provable to be true
3. provable to be false
4. a certainty
5. a logical process
11. Imagine that a distribution is not a normal distribution. However, the sampling distribution of means approaches a normal distribution as the sample size increases. This statement
1. is patently false. As the sample size increases, the sampling distribution of means becomes less and less like a normal distribution
2. is true only if the original distribution is almost a normal distribution
3. is true only for small populations
4. is true only for large populations
5. is true because of the Central Limit Theorem
12. Imagine that you want to determine the quantitative effect (if any) that salt consumption has on people's blood pressure. You interview 100 people from each continent in the world, ask them how much salt they eat, and then measure their blood pressures with instruments obtained from, and calibrated by, a respected medical school. Which of the following possible flaws in this experiment should you be the least concerned about?
1. People might not accurately know how much salt they eat.
2. The blood pressure measuring equipment might not show correct readings.
3. The sampling frame is too small.
4. The sample might be biased relative to such factors as age, gender, or ethnicity.
5. You need not be concerned about any of the factors (a), (b), (c), or (d).
13. Table Test 2-2 illustrates the average monthly temperatures and rainfall amounts for an imaginary city in the Southern Hemisphere called Rio de Antonio. From this table it is apparent that
1. there is no correlation between the average monthly temperature and the average monthly rainfall
2. there is a significant correlation between the average monthly temperature and the average monthly rainfall
3. there is no correlation between the time of year and the average monthly rainfall
4. there is a significant correlation between the time of year and the average monthly rainfall
5. more than one of the above
14. Refer to Table Test 2-2 and Fig. Test 2-2. Which of the graphs in Fig. Test 2-2 most nearly represents the line of least squares for a scatter plot of the relationship between the average monthly temperature and the average monthly rainfall for Rio de Antonio? Assume that on each plot, temperatures increase as you move to the right along the horizontal scale, and rainfall amounts increase as you move up along the vertical scale.
1. A
2. B
3. C
4. D
5. None of them
15. Imagine that a correlation of ri = –0.500 is found between the average number of minutes per day people use the Internet and the average number of minutes per day they spend reading books. The time people spend on the Internet is the independent variable, and the time they spend reading books is the dependent variable. If the independent and dependent variables are interchanged, what is the correlation rr between them?
1. rr = –0.500
2. rr = 0
3. rr = +0.500
4. rr = –2.00
5. rr = +2.00
16. In a bar graph, what is the advantage of showing the numbers (if there's room) at the ends or the tops of the bars?
1. It makes the graph appear less cluttered.
2. It eliminates bias in the experiment.
3. It tells the observer exactly how tall or wide the bars are.
4. It turns the graph into a point-to-point plot.
5. There is no advantage in doing this.
17. The possible range of correlation values between two variables is
1. –50% to +50%
2. –100% to 0%
3. –100% to +100%
4. 0% to 100%
5. none of the above
18. The level of significance is the probability that the null hypothesis will turn out to be true
1. after it has been rejected
2. after it has been accepted
3. after all the alternative hypotheses have been rejected
4. provided all the alternative hypotheses are also true
5. provided some of the alternative hypotheses are also true
19. The level of significance can be expressed as
1. a value less than –1
2. a value between –1 and 1
3. a value between –1 and 0
4. a value between 0 and 1
5. a value greater than 1
20. If data are already available and all a statistician has to do is organize it and analyze it, then it is called
1. analyzed source data
2. secondary source data
3. estimated source data
4. correlated source data
5. prepared source data
21. Experimental defect error can be caused by
1. replacing elements when they should not be replaced
2. failing to replace elements when they should be replaced
3. attempting to compensate for factors that don't have any real effect
4. a sample that is not large enough
5. any of the above
22. What is the technical term for the type of graph shown in Fig. Test 2-3?
1. A curvature plot.
2. A relational plot.
3. A scatter plot.
4. A correlative plot.
5. A least-squares plot.
23. What can be said about the correlation r between Parameter X and Parameter Y in Fig. Test 2-3?
1. –1 < r < 0
2. 0 < r < +1
3. r = –1
4. r = +1
5. r = 0
24. Suppose a computer were used in an attempt to locate the least-squares line in Fig. Test 2-3. What would be the orientation of the resulting line?
1. It would ramp downward as you move toward the right.
2. It would ramp upward as you move toward the right.
3. It would be vertical.
4. It would be horizontal.
5. It would coincide exactly with the dashed curve.
25. Suppose a correlation of rk = +0.4825 is found between the speed, in kilometers per hour, at which a car is driven and the average number of traffic accidents per hour. One statute mile is about 1.609 kilometers. Given this information, what is the approximate correlation rm between the speed, in statute miles per hour, at which a car is driven and the average number of traffic accidents per hour?
1. rm = +0.7763
2. rm = +0.2999
3. rm = +0.4825
5. It can't be defined because the units have changed.
26. If a distribution is bimodal, it means that
1. there are two entirely different curves that can represent it
2. the data is ambiguous
3. there are two different values of the independent variable for which the dependent variable reaches a maximum
4. there are two different values of the dependent variable for which the independent variable reaches a minimum
5. there are two different but equally valid values for the median
27. Imagine that a correlation of ri = –0.500 is found between the average number of minutes per day people use the Internet and the average number of minutes per day they spend reading books. This logically and rigorously implies
1. that Internet usage causes people to spend more time reading books
2. that Internet usage causes people to spend less time reading books
3. that book reading causes people to spend more time on the Internet
4. that book reading causes people to spend less time on the Internet
5. none of the above
28. Which of the following methods is best for generating pseudorandom digits?
1. Repeatedly spin a wheel calibrated in digits from 0 to 9, with each digit having the same angular space (36° of arc) around the circle.
2. Have a child utter digits from 0 to 9 aloud for an indefinite period of time, after being told to say them at random.
3. Throw darts at a checker board with squares labeled with digits from 0 to 9, with each square having equal area, there being an equal number of squares for each of the digits 0 through 9.
4. Place 10 marbles, one labeled with each digit 0 to 9, in a jar, shake the jar for a minute, then close your eyes and pick a marble out. Repeat this process for each digit needed.
5. None of the above methods is any good at all.
29. A regression curve shows
1. the extent of the inference for a specific hypothesis
2. the general way in which two variables are related
3. the probability that the null hypothesis is true
4. the probability that a specific alternative hypothesis is true
5. nothing significant unless it is a straight line
30. Figure Test 2-4 shows the 95% confidence interval in a normal distribution. This means that
1. the area under the curve between the light dashed vertical line on the left and the light dashed vertical line on the right is equal to 95% of the total area under the curve
2. the area under the curve between the light dashed vertical line on the left and the heavy dashed vertical line in the center is equal to 95% of the total area under the curve
3. the area under the curve between the heavy dashed vertical line in the center and the light dashed vertical line on the right is equal to 95% of the total area under the curve
4. the total area under the curve is 95%
5. none of the above
31. Suppose, in Fig. Test 2-4, the light, vertical dashed lines represent the mean plus-or-minus 3 standard deviations, rather than the mean plus-or-minus 2 standard deviations. Then the graph would portray
1. a 68% confidence interval
2. a 95% confidence interval
3. a 99.7% confidence interval
4. a 100% confidence interval
5. a confidence interval that cannot be defined
32. Imagine there has been a heavy snowfall. You are about to use the snow blower to remove the snow from your driveway. You say, "It will take me exactly 30 minutes to clear the snow from the driveway." Your older sister says, "It will take you longer than that." Your sister's hypothesis is
1. the null hypothesis
2. a one-sided alternative hypothesis
3. a two-sided alternative hypothesis
4. impossible to prove
5. valid only if you don't own a snow blower
33. The line of least squares in a scatter plot is always
1. a circle
2. a parabola
3. straight
4. horizontal
5. vertical
34. The tendency for small events to have dramatic long-term and largescale consequences is called
1. correlation magnification
2. the Mandelbrot effect
3. the butterfly effect
4. regression
5. standard deviation
35. Which of the following is not a measure of central tendency in a statistical distribution?
1. The mean.
2. The median.
3. The mode.
4. The dependent variable.
5. All of the above are measures of central tendency in a statistical distribution.
36. In a statistical distribution, the standard deviation is equal to
1. the square root of the mean
2. the square root of the variance
3. the square root of the median
4. the square root of the mode
5. any of the above
37. Random sampling is done in an attempt to
1. generate a random-number table
2. get an unbiased cross-section of a population
3. distort or skew the results of a statistical experiment
4. ensure that a distribution is normal
5. define a confidence interval
38. Imagine tossing a pair of identical, unbiased, 6-sided dice. What is the probability that both dice will come up showing 2?
1. 1 in 2
2. 1 in 6
3. 1 in 12
4. 1 in 36
5. 1 in 72
39. The standard deviation in a statistical distribution is a measure of
1. dispersion
2. central tendency
3. independent variation
4. dependent variation
5. the mode
40. The fact that events often occur in bunches, and the fact that improvement in athletic performance often takes place in spurts rather than steadily and gradually, are explainable according to
1. the law of averages
2. statistical distributions
3. probability theory
4. chaos theory
5. the theory of the least upper bound
41. A sampling frame is
1. a point of view from which a statistical experiment is done
2. a range of dependent-variable values
3. the same thing as a confidence interval
4. a set of items within a population from which a sample is chosen
5. a single element in a population
42. Suppose you step on a digital scale that displays your weight in pounds, all the way down to the hundredth of a pound. You are told the scale is accurate to within ±1%. The scale indicates your weight as 120.00 pounds. This means your actual weight could be anywhere between
1. 119.99 and 120.01 pounds
2. 119.88 and 120.12 pounds
3. 118.80 and 121.20 pounds
4. 108.00 and 132.00 pounds
43. Refer to the correlation plot of Fig. Test 2-5. Suppose the dashed line represents the least-squares line for all the solid black points. If a new value is added in the location shown by the gray point P, but no other new values are added, what will happen to the least-squares line?
1. It will vanish.
2. It will move up from the position shown.
3. It will move down from the position shown.
4. Its position will not change from that shown.
44. Refer to the correlation plot of Fig. Test 2-5. Suppose the dashed line represents the least-squares line for all the solid black points. If a new value is added in the location shown by the gray point Q, but no other new values are added, what will happen to the least-squares line?
1. It will vanish.
2. It will move up from the position shown.
3. It will move down from the position shown.
4. Its position will not change from that shown.
45. Refer to the correlation plot of Fig. Test 2-5. Suppose the dashed line represents the least-squares line for all the solid black points. If a new value is added in the location shown by the gray point R, but no other new values are added, what will happen to the least-squares line?
1. It will vanish.
2. It will move up from the position shown.
3. It will move down from the position shown.
4. Its position will not change from that shown.
46. Imagine tossing a pair of identical, unbiased, 6-sided dice. What is the probability that both dice will come up showing the same number of dots?
1. 1 in 2
2. 1 in 6
3. 1 in 12
4. 1 in 36
5. 1 in 72
47. Suppose a scatter plot shows a strong negative correlation between two variables. How many least-squares lines can exist for this plot?
1. None.
2. One.
3. Two.
4. More than two.
5. Infinitely many.
48. Refer to Fig. Test 2-6. What is the probability that the randomly chosen point lies within 3 standard deviations of the mean?
1. 68%
2. 95%
3. 99.7%
4. Somewhere between 68% and 95%
5. Somewhere between 95% and 99.7%
49. There are two major ways in which an error can be made when formulating hypotheses. One type of error involves rejecting or denying the potential truth of a null hypothesis, and then having the experiment show that it's true. The other major type of blunder is to
1. reject all the alternative hypotheses, and then have the null hypothesis turn out to be true
2. take a random sample of the population when it's better to take a biased sample
3. take a population sample that is too large, resulting in an inadequate cross-sectional representation
4. accept the null hypothesis and then have the experiment show that it's false
5. accept all the alternative hypotheses, and have them all turn out true
50. Refer to Fig. Test 2-7. What, if anything, is wrong with this graph?
1. Nothing is wrong. It's perfectly all right.
2. The plots for the absolute frequency and the cumulative absolute frequency are labeled wrong, although the axes are labeled correctly.
3. The axes for the absolute frequency and the cumulative absolute frequency are labeled wrong, although the plots are labeled correctly.
4. Both the axes and the plots for the absolute frequency and the cumulative absolute frequency are labeled wrong.
5. Absolute frequency and cumulative absolute frequency can never be plotted together in the same graph, so there's no way to make it correct.
51. Suppose you flip a coin 20 times. What is the probability that the coin will come up "heads" on all 20 flips? Assume the coin is not "weighted," so the probability of it coming up "heads" on any given flip is 50%.
1. 1 in 20
2. 1 in 48
3. 1 in 256
4. 1 in 512
5. None of the above
52. Refer to Table Test 2-3. This shows the results of a hypothetical 10-question test given to a large class of students. What score represents the mode?
1. 5
2. 6
3. 45
4. 59
5. 262
53. Table Test 2-4 shows the results of the same hypothetical test as that portrayed in Table Test 2-3. What is wrong with Table Test 2-4?
1. The absolute frequency values don't add up correctly.
2. The cumulative absolute frequency values don't add up correctly.
3. There exists no mean.
4. There exists no median.
5. Nothing is wrong with this table. It is perfectly plausible.
54. In Tables Test 2-3 and Test 2-4, what score represents the median?
1. 5
2. 6
3. 45
4. 59
5. 262
55. In a vertical bar graph, the independent variable is normally portrayed
1. along the horizontal axis
2. along the vertical axis
3. as the heights of various rectangles or bars
4. as the widths of various rectangles or bars
5. as a smooth curve
56. In a horizontal bar graph, the independent variable is normally portrayed
1. as the heights of various rectangles or bars
2. as the widths of various rectangles or bars
3. along the horizontal axis
4. along the vertical axis
5. as a smooth curve
57. Fill in the following sentence to make it the most accurate: "It's possible to _ _________ express the correlation between two variables if one or both of them cannot be quantified."
1. precisely
2. qualitatively
3. inversely
4. numerically
5. logically
58. Once in a while, you'll see a scatter plot in which almost all of the points lie near a straight line, but there are a few points that are far away from the main group. Stray points of this sort are called
1. wingers
2. uncorrelaters
3. nonconformers
4. outliers
5. scatterers
59. What is the maximum possible number of hypotheses in a scenario?
1. One: the null hypothesis.
2. Two: the null hypothesis and the alternative hypothesis.
3. Three: the null hypothesis, a one-sided alternative hypothesis, and a two-sided alternative hypothesis.
4. Four: the null hypothesis, two one-sided alternative hypotheses, and a two-sided alternative hypothesis.
5. It is impossible to answer this question without knowing more about the scenario.
60. Suppose you want to determine the average (mean) time that Canadian postal workers get out of bed in the morning. You conduct a survey of 50 postal workers in various Canadian cities and towns, and find that the average time they arise is 6:18 A.M. This time is
1. a population of the mean
2. an estimate of the mean
3. precisely equal to the mean
4. a sampling frame of the mean
5. a meaningless statistic

1. c
2. a
3. d
4. e
5. a
6. b
7. b
8. e
9. a
10. a
11. e
12. b
13. e
14. a
15. a
16. c
17. c
18. a
19. d
20. b
21. e
22. c
23. a
24. a
25. c
26. c
27. e
28. d
29. b
30. a
31. c
32. b
33. c
34. c
35. d
36. b
37. b
38. d
39. a
40. d
41. d
42. c
43. c
44. d
45. b
46. b
47. b
48. c
49. d
50. d
51. e
52. b
53. e
54. b
55. a
56. d
57. b
58. d
59. e
60. b

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