agiebailley posted a question
A sample has a mean of M = 70. If one person with a score of X = 50 is added to the sample, what effect will it have on the sample mean?
Answer
A. cannot be determined from the information given
B. the sample mean will decrease
C. the sample mean will increase
D. the sample mean will stay the same

a. 288
b. 48
c. 12
d. 8
Save Answer

2.
(Points: 5)
For the population of scores shown in the frequency distribution table, the mean is_____. X = 5 f = 2, X = 4 f = 1, X = 3 f = 4, X = 2 f = 3, X = 1 f = 2

a. 15/5 = 3
b. 12/12 = 1.25
c. 34/5 = 6.68
d. 34/12 = 2.83
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3.
(Points: 5)
A population has a mean of 4 and SX = 48. How many scores are in this population? (Assume S = the summation symbol)

a. 192
b. 48
c. 12
d. cannot be determined from the information given
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4.
(Points: 5)
After 5 points are added to every score in a distribution, the mean is calculated and the new mean is found to be = 30. What was the value of the mean for the original distribution?

a. 25
b. 30
c. 35
d. cannot be determined from the information given
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5.
(Points: 5)
Changing the value of a score in a distribution will always change the value of the ____.

a. mean
b. median
c. mode
d. all of the choices are correct
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6.
(Points: 5)
A sample has a mean of M = 72. If one person with a score of X = 58 is removed from the sample, what effect will it have on the sample mean?

a. The sample mean will increase.
b. The sample mean will decrease.
c. The sample mean will remain the same.
d. cannot be determined from the information given
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7.
(Points: 5)
What is the value of the median for the following set of scores? Scores: 1, 3, 3, 5, 6, 7, 8, 23

a. 5
b. 5.5
c. 6
d. 54/8 = 7
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8.
(Points: 5)
What is the median for the following set of scores? Scores: 1, 2, 5, 6, 17

a. 3.5
b. 5
c. 5.5
d. 6
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9.
(Points: 5)
A teacher gave a reading test to a class of 5th-grade students and computed the mean, median, and mode for the test scores. Which of the following statements cannot be an accurate description of the scores?

a. The majority of the students had scores above the mean.
b. The majority of the students had scores above the median.
c. The majority of the students had scores above the mode.
d. All of the other options are false statements.
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10.
(Points: 5)
One item on a questionnaire asks, "How many siblings (brothers and sisters) did you have when you were a child?" A researcher computes the mean, the median, and the mode for a set of n = 50 responses to this question. Which of the following statements accurately describes the measures of central tendency?

a. Because the scores are all whole numbers, the mean will be a whole number.
b. Because the scores are all whole numbers, the median will be a whole number.
c. Because the scores are all whole numbers, the mode will be a whole number.
d. All of the other options are correct descriptions.
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11.
(Points: 5)
What is the mode for the following sample of n = 8 scores? Scores: 0, 1, 1, 2, 2, 2, 2, 3

a. 2
b. 2.5
c. 13/8 = 1.625
d. 5
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12.
(Points: 5)
One sample of n = 4 scores has a mean of M = 10, and a second sample of n = 8 scores has a mean of M = 20. If the two samples are combined, the mean for the combined sample will be ____.

a. equal to 15
b. greater than 15 but less than 20
c. less than 15 but more than 10
d. None of the other choices is correct.
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13.
(Points: 5)
One sample has n = 10 scores and M = 30. A second sample has n = 20 scores and M = 40. If the two samples are combined, then the combined sample will have a mean ____.

a. halfway between 30 and 40.
b. closer to 30 than it is to 40.
c. closer to 40 than it is to 30.
d. None of the other choices is correct.
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14.
(Points: 5)
Which of the following is true for a symmetrical distribution?

a. The mean, median, and mode are all equal.
b. mean = median
c. mean = mode
d. median = mode
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15.
(Points: 5)
For a negatively skewed distribution with a mode of X = 25 and a mean of M = 20, the median is probably ____.

a. greater than 25
b. less than 20
c. between 20 and 25
d. cannot be determined from the information given
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16.
(Points: 5)
For a negatively skewed distribution with a mode of X = 25 and a median of 20, the mean is probably ____.

a. greater than 25
b. less than 20
c. between 20 and 25
d. cannot be determined from the information given
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17.
(Points: 5)
A distribution is positively skewed. Which is the most probable order for the three measures of central tendency?

a. mean = 40, median = 50, mode = 60
b. mean = 60, median = 50, mode = 40
c. mean = 40, median = 60, mode = 50
d. mean = 50, median = 50, mode = 50
Save Answer

18.
(Points: 5)
A researcher is measuring problem-solving times for a sample of n = 20 children. However, one of the children fails to solve the problem, so the researcher has an undetermined score. What is the best measure of central tendency for these data?

a. the mean
b. the median
c. the mode
d. Central tendency cannot be determined for these data.
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19.
(Points: 5)
A set of individuals is measured on a nominal scale. To determine the central tendency for the resulting measurements, a researcher should use the ______.

a. mean
b. median
c. mode
d. It is impossible to determine central tendency for nominal measurements.
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20.
(Points: 5)
For an extremely skewed distribution of scores, the best measure of central tendency would be ____.

a. the mean
b. the median
c. the mode
d. Central tendency cannot be determined for a skewed distribution.





A sample consists of n=16 scores. How many of the scores are used to calculate the sample variance?

a. 2
b. 8
c. 15
d. all 16
Save Answer

2.
(Points: 5)
The value for the interquartile range is determined by _________.

a. the extreme scores (both high and low) in the distribution
b. the extremely high scores in the distribution
c. the middle scores in the distribution
d. all the scores in the distribution
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3.
(Points: 5)
Scores from a statistics exam are reported as deviation scores. Which of the following deviation scores indicated a higher position in the class distribution.

a. +8
b. 0
c. -8
d. can not determine without more information
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4.
(Points: 5)
What value is obtained if you add all the deviation scores for a population, then divide the sum by N?

a. the population variance
b. the population standard deviation
c. you always will get zero
d. None of the other choices is correct
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5.
(Points: 5)
The symbol SS stands for the _________.

a. the sum of squared scores
b. sum of squared deviations
c. sum of the scores squared
d. sum of the deviiations squared
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6.
(Points: 5)
Which of the following symbols identifies the sample standard deviation

a. s
b. s2 (squared)
c. the "theta" symbol
d. the "theta" symbol squared
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7.
(Points: 5)
Which of the following symbols identifies the population variance?

a. s
b. s2 (squared)
c. theta symbol
d. sigma symbol squared
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8.
(Points: 5)
For a population of N = 10 scores, you first measure the distance between each score and the mean, then square each distance and find the sum of the squared distances. At this point you have calculated __________.

a. SS
b. the population variance
c. the population standard deviation
d. he other choices is correct
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9.
(Points: 5)
The sum of the squared deviation scores is SS = 60 for a sample of n = 5 scores. What is the variance for this sample?

a. 60/5 = 12
b. 60/4 = 15
c. 5(60) = 300
d. 4(60) = 240
Save Answer

10.
(Points: 5)
What does it mean to say that the sample variance is an unbiased statistic?

a. No sample will have a variance that is exactly equal to the poplation variance
b. Each sample will have a variance that is equal to the population variance.
c. If many different samples are selected, the average of the sample variances will be equal to the population variance
d. If many different samples are selected, the sample variances will consistently underestimate the population variance
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11.
(Points: 5)
A population of scores has m = 50 and standard deviation = 10. If 5 points are added to every score in the population, then the new mean and standard deviation would be ____. Assume that m = the "mu" symbol.

a. m=50 and standard deviation 10
b. m = 55 and standard deviation = 10
c. m = 50 and standard deviation = 15
d. m = 55 and standard deviation = 15
Save Answer

12.
(Points: 5)
A population of scores has m = 50 and standard deviation = 10. If every score in the population is multiplied by 2, then the new mean and standard deviation would be ____. Assume the m = the "mu" symbol.

a. m = 50 and standard deviation = 10
b. m = 100 and standard deviation = 10
c. m = 50 and standard deviation = 20
d. m = 100 and standard deviation = 20
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13.
(Points: 5)
A population has m = 40 and standard deviation = 8. If each score is divided by 2, the new standard deviation will be ____. Assume m = the "mu" symbol.

a. 20
b. 8
c. 4
d. insufficient information, cannot be determined
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14.
(Points: 5)
A population of scores has m = 50 and s = 12. If you subtract five points from every score in the population, then the new standard deviation will be ____. Assume that m = the "mu" symbol.

a. 7
b. 12
c. 45
d. insufficient information, cannot be determined
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15.
(Points: 5)
A population of N = 10 scores has a mean of 24 with SS = 160, a variance of 16, and a standard deviation of 4. For this population, S(X- m)2 (m = "mu" symbol and equation is squared) has a value of ____.

a. 0
b. 4
c. 16
d. 160
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16.
(Points: 5)
What is the value of SS for the following set of scores? Scores: 1, 1, 1, 3

a. 3
b. 6
c. 12
d. 36
Save Answer

17.
(Points: 5)
What is the variance for the following population of scores? 5,2,5,4

a. 6
b. 2
c. 1.5
d. 1.22
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18.
(Points: 5)
Which set of scores has the smallest standard deviation?

a. 11, 17, 31, 53
b. 5, 11, 42, 22
c. 145, 143, 145, 147
d. 27, 105, 10, 80
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19.
(Points: 5)
For a particular sample, the largest distance (deviation) between a score and the mean is 11 points. The smallest distance between a score and the mean is 4 points. Therefore, the standard deviation ____.

a. will be less than 4
b. will be between 4 and 11
c. will be greater than 11
d. It is impossible to say anything about the standard deviation.
Save Answer

20.
(Points: 5)
The smallest score in a population is X = 5 and the largest score is X = 10. Based on this information, you can conclude that ____.

a. the population mean is somewhere between 5 and 10
b. the population standard deviation is smaller than 6
c. the population mean is between 5 and 10, and the standard deviation is less than 6
d. None of the other choices are correct.



1.
(Points: 5)
In a distribution with mean = 50 and standard deviation = 10, a score of X = 55 corresponds to a z-score of z = +0.50.

a. True
b. False
Save Answer

2.
(Points: 5)
In a distribution with mean = 50 and standard deviation = 10, a score of X = 30 corresponds to a z-score of z = -3.00.

a. True
b. False
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3.
(Points: 5)
In a distribution with mean = 80 and standard deviation = 20, a score of X = 85 corresponds to a z-score of z = 1.50.

a. True
b. False
Save Answer

4.
(Points: 5)
In a distribution with mean = 40 and standard deviation = 12, a z-score of z = -0.50 corresponds to a score of X = 46.

a. True
b. False
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5.
(Points: 5)
In a distribution with standard deviation = 8, a score of X = 64 corresponds to z = -0.50. The mean for this population is 60.

a. True
b. False
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6.
(Points: 5)
On an exam, Tom scored 8 points above the mean and had a z-score of +2.00. The standard deviation for the
set of exam scores must be 4.

a. True
b. False
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7.
(Points: 5)
If a population of N = 10 scores is transformed into z-scores, there will be five positive z-scores and five
negative z-scores.

a. True
b. False
Save Answer

8.
(Points: 5)
If a distribution of scores is transformed into z-scores then the sum of the positive z-scores will be exactly
equal to the sum of the negative z-scores (ignoring the signs).

a. True
b. False
Save Answer

9.
(Points: 5)
Transforming X values into z-scores will not change the shape of the distribution.

a. True
b. False
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10.
(Points: 5)
Whenever a population is transformed into z-scores, the mean of the z-scores is equal to 0.

a. True
b. False
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11.
(Points: 5)
A z-score of z = -2.00 indicates a position in a distribution ______.

a. above the mean by 2 points
b. above the mean by a distance equal to 2 standard deviations
c. below the mean by 2 points
d. below the mean by a distance equal to 2 standard deviations
Save Answer

12.
(Points: 5)
For a population with mean = 80 and standard deviation = 10, the z-score corresponding to X = 85 would be ______.

a. +0.50
b. +1.00
c. +2.00
d. +5.00
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13.
(Points: 5)
For a population with mean = 60 and standard deviation = 8, the X value corresponding to z = -0.50 would be ______.

a. -4
b. 56
c. 64
d. 59.5
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14.
(Points: 5)
A population of scores has mean = 44. In this population, an X value of 40 corresponds to z = -0.50. What is the
population standard deviation?

a. 2
b. 2
c. 8
d. 6
Save Answer

15.
(Points: 5)
A population of scores has mean = 50. In this population, an X value of 58 corresponds to z = 2.00. What is the
population standard deviation?

a. 2
b. 4
c. 8
d. 16
Save Answer

16.
(Points: 5)
A population of scores has standard deviation = 20. In this population, a score of X = 80 corresponds to z = +0.25. What is the population mean?

a. 70
b. 75
c. 85
d. 90
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17.
(Points: 5)
A z-score of z = -0.25 indicates a location that is ______.

a. at the center of the distribution
b. slightly below the mean
c. far below the mean in the extreme left-hand tail of the distribution
d. The location depends on the mean and standard deviation for the distribution.
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18.
(Points: 5)
A population with mean = 85 and standard deviation = 12 is transformed into z-scores. After the transformation, the population of z-scores will have a mean of _____.

a. 85
b. 1.00
c. 0
d. cannot be determined from the information given
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19.
(Points: 5)
A distribution with mean = 35 and standard deviation = 8 is being standardized so that the new mean and standard deviation will be mean = 50 and standard deviation = 10. When the distribution is standardized, what value will be obtained for a score of X = 39 from the original distribution?

a. X = 54
b. X = 55
c. X = 1.10
d. impossible to determine without more information
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20.
(Points: 5)
Using z-scores, a population with mean = 37 and standard deviation = 8 is standardized so that the new mean is mean = 50 and standard deviation = 10. How does an individual's z-score in the new distribution compare with his/her z-score in the original population?

a. new z = old z + 13
b. new z = (10/6)(old z)
c. new z = old z
d. cannot be determined with the information given



1.
(Points: 5)
As defined in the text, random sampling requires that each individual in the population has an equal chance of being selected.

a. True
b. False
Save Answer

2.
(Points: 5)
As defined in the text, random sampling requires sampling with replacement.

a. True
b. False
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3.
(Points: 5)
A jar contains 10 red marbles and 20 blue marbles. If you take a random sample of two marbles from this jar, then the probability that the second marble is blue is exactly equal to the probability that the first marble is blue.

a. True
b. False
Save Answer

4.
(Points: 5)
A jar contains 10 red marbles and 20 blue marbles. If you take a random sample of two marbles from this jar, then the probability that the second marble is blue depends on the color of the first marble.

a. True
b. False
Save Answer

5.
(Points: 5)
For any normal distribution, the mean and the median will have the same value.

a. True
b. False
Save Answer

6.
(Points: 5)
The Unit Normal Table can be used for any normal distribution, no matter what the values are for the mean and standard deviation.

a. True
b. False
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7.
(Points: 5)
The Unit Normal Table lists proportions for any distribution, provided that the distribution has been transformed into z-scores.

a. True
b. False
Save Answer

8.
(Points: 5)
When determining the probability of selecting a score that is below the mean, you will get a negative value for probability.

a. True
b. False
Save Answer

9.
(Points: 5)
For any normal distribution, the proportion corresponding to scores greater than z = +1.00 is exactly equal to the proportion corresponding to scores less than z = -1.00.

a. True
b. False
Save Answer

10.
(Points: 5)
For any normal distribution, the proportion in the tail beyond z = -2.00 is p = -0.0228.

a. True
b. False
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11.
(Points: 5)
For a normal distribution, the proportion in the tail beyond z = 1.50 is p = 0.0668. Based on this information, what is the proportion in the tail beyond z = -1.50?

a. 0.0668
b. -0.0668
c. 0.9332
d. -0.9332
Save Answer

12.
(Points: 5)
What proportion of a normal distribution is located in the tail beyond z = 2.00?

a. 1.14%
b. 2%
c. 2.28%
d. 97.72%
Save Answer

13.
(Points: 5)
What proportion of the scores in a normal distribution correspond to z-scores greater than +1.04?.

a. 0.3508
b. 0.1492
c. 0.6492
d. 0.8508
Save Answer

14.
(Points: 5)
What proportion of the scores in a normal distribution have z-scores less than z = 0.86?

a. 0.3051
b. 0.1949
c. 0.8051
d. 0.6949
Save Answer

15.
(Points: 5)
What proportion of the scores in a normal distribution have z-scores less than z = -1.32?

a. 0.0934
b. 0.4066
c. 0.5934
d. 0.9066
Save Answer

16.
(Points: 5)
What proportion of the scores in a normal distribution have z-scores greater than z = -1.25?

a. 0.1056
b. -0.1056
c. 0.8944
d. -0.8944
Save Answer

17.
(Points: 5)
For a normal distribution, what z-score value separates the highest 10% of the distribution from the lowest 90%?

a. z = 0.90
b. z = -0.90
c. z = 1.28
d. z = -1.28
Save Answer

18.
(Points: 5)
For a normal distribution with a mean of mean = 40 and standard deviation = 4, what is the probability of sampling an individual with a score greater than 46?

a. 0.0668
b. 0.4452
c. 0.9332
d. 0.0548
Save Answer

19.
(Points: 5)
For a normal distribution with a mean of mean = 60 and standard deviation = 8, what is the probability of selecting an individual with a score less than 54?

a. 0.2266
b. 0.7734
c. 0.7266
d. 0.2734
Save Answer

20.
(Points: 5)
A normal distribution has a mean of mean = 500 and standard deviation = 100. What score is needed to place in the top 20% of the distribution?

a. 520
b. 580
c. 584
d. 700

wo samples probably will have different means even if they are both the same size and they are both selected from the same population.

a. True
b. False
Save Answer

2.
(Points: 5)
According to the Central Limit Theorem, the expected value for a sample mean approaches zero as the sample size approaches infinity.

a. True
b. False
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3.
(Points: 5)
The mean of the distribution of sample means is called the standard error of the mean.

a. True
b. False
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4.
(Points: 5)
The standard error of the mean can never be greater than the standard deviation of the population from which the sample is selected.

a. True
b. False
Save Answer

5.
(Points: 5)
On average, a sample of n = 100 scores will provide a better estimate of the population mean than a sample of n = 50 scores.

a. True
b. False
Save Answer

6.
(Points: 5)
Assuming that all other factors are held constant, as the population variability increases, the standard error also increases.

a. True
b. False
Save Answer

7.
(Points: 5)
A sample of n = 25 scores has a standard error of 2. This sample was selected from a population with mean = 50.

a. True
b. False
Save Answer

8.
(Points: 5)
A population has mean = 50 and standard deviation = 10. For a sample of n = 4 scores from this population, a sample mean of = 55 would be considered an extreme value.

a. True
b. False
Save Answer

9.
(Points: 5)
A population has mean = 50 and standard deviation = 10. For a sample of n = 100 scores from this population, a sample mean = 55 would be considered an extreme value.

a. True
b. False
Save Answer

10.
(Points: 5)
A researcher obtained mean = 33 for a sample of n = 16 scores selected from a population with mean = 30 and standard deviation = 12. This sample mean corresponds to a z-score of z = 1.00.

a. True
b. False
Save Answer

11.
(Points: 5)
The mean of the distribution of sample means is called ______.

a. the expected value of the sample mean
b. the standard error of the mean
c. the sample mean
d. the central limit mean
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12.
(Points: 5)
The standard deviation of the distribution of sample means is called ______.

a. the expected value of the sample mean
b. the standard error of the mean
c. the sample standard deviation
d. the central limit standard deviation
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13.
(Points: 5)
When the sample size is greater than n = 30 ______.

a. the distribution of sample means will be approximately normal
b. the sample mean will be equal to the population mean
c. all of the above
d. none of the above
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14.
(Points: 5)
The standard error of the mean provides a measure of ______.

a. the maximum possible discrepancy between the sample and population means
b. the minimum possible discrepancy between the sample and population means
c. the exact discrepancy between each specific sample mean and the population mean
d. none of the above
Save Answer

15.
(Points: 5)
As sample size increases, the expected value of the sample mean ______.

a. also increases
b. decreases
c. stays constant
d. approaches the value of the population mean
Save Answer

16.
(Points: 5)
As sample size increases, the standard error of the mean ______.

a. also increases
b. decreases
c. stays constant
d. approaches the value of the population mean
Save Answer

17.
(Points: 5)
For a population with mean = 80 and standard deviation = 20, the distribution of sample means based on n = 16 will have an expected value of ______.

a. 5
b. 15
c. 20
d. 80
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18.
(Points: 5)
In general, the standard error of the mean gets smaller as ______.

a. sample size and standard deviation both increase
b. sample size and standard deviation both decrease
c. sample size increases and standard deviation decreases
d. sample size decreases and standard deviation increases
Save Answer

19.
(Points: 5)
A random sample of n = 4 scores is obtained from a normal population with mean = 20 and standard deviation = 4. What is the probability of obtaining a mean greater than 22 for this sample?

a. 0.50
b. 1.00
c. 0.1587
d. 0.3085
Save Answer

20.
(Points: 5)
If sample size (n) is held constant, the standard error will _______ as the population variance increases.

a. increase
b. decrease
c. stay constant
d. cannot answer with the information given