Chapter 3

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Which of the following symbols represents the variance of the population? a. 2 b. c. d.

a. 2

The most important statistical descriptive measure of the location of a data set is the a. mean b. median c. mode d. variance

a. mean

Which of the following is not a measure of dispersion? a. mode b. standard deviation c. range d. interquartile range

a. mode

In computing the mean of a sample, the value of xi is divided by a. n b. n - 1 c. n + 1 d. n - 2

a. n

The 75th percentile is referred to as the a. first quartile b. second quartile c. third quartile d. fourth quartile

c. third quartile

The variance of a sample of 169 observations equals 576. The standard deviation of the sample equals a. 13 b. 24 c. 576 d. 28,461

b. 24

Refer to Exhibit 3-5. The standard deviation is a. 570 b. 5.477 c. 25 d. 30

b. 5.477

In computing descriptive statistics from grouped data, a. data values are treated as if they occur at the midpoint of a class b. the grouped data result is more accurate than the ungrouped result c. the grouped data computations are used only when a population is being analyzed d. None of these alternatives is correct.

a. data values are treated as if they occur at the midpoint of a class

When data are positively skewed, the mean will usually be a. greater than the median b. smaller than the median c. equal to the median d. positive

a. greater than the median

Refer to Exhibit 3-1. The relative frequency of students working 9 hours or less a. is .2 b. is .45 c. is 40 d. cannot be determined from the information given

a. is .2

The pth percentile is a value such that at least p percent of the observations are a. less than or equal to this value b. less than this value c. more than or equal to this value d. more than this value

a. less than or equal to this value

When the data are skewed to the right, the measure of Skewness will be a. negative b. zero c. positive d. one

c. positive

The difference between the largest and the smallest data values is the a. variance b. interquartile range c. range d. coefficient of variation

c. range

A numerical value used as a summary measure for a sample, such as sample mean, is known as a a. population parameter b. sample parameter c. sample statistic d. population mean

c. sample statistic

In a five number summary, which of the following is not used for data summarization? a. the smallest value b. the largest value c. the mean d. the 25th percentile

c. the mean

The measure of dispersion that is influenced most by extreme values is a. the variance b. the standard deviation c. the range d. the interquartile range

c. the range

The interquartile range is used as a measure of variability to overcome what difficulty of the range? a. the sum of the range variances is zero b. the range is difficult to compute c. the range is influenced too much by extreme values d. the range is negative

c. the range is influenced too much by extreme values

The symbol is used to represent a. the variance of the population b. the standard deviation of the sample c. the standard deviation of the population d. the variance of the sample

c. the standard deviation of the population

When the smallest and largest percentage of items are removed from a data set and the mean is computed, the mean of the remaining data is a. the median b. the mode c. the trimmed mean d. any of the above

c. the trimmed mean

Which of the following is not a measure of central location? a. mean b. median c. variance d. mode

c. variance

The value of the sum of the deviations from the mean, i.e., must always be a. less than the zero b. negative c. either positive or negative depending on whether the mean is negative or positive d. zero

d. zero

The descriptive measure of dispersion that is based on the concept of a deviation about the mean is a. the range b. the interquartile range c. the absolute value of the range d. the standard deviation

d. the standard deviation

The measure of dispersion which is not measured in the same units as the original data is the a. median b. standard deviation c. coefficient of determination d. variance

d. variance

Refer to Exhibit 3-3. The range is a. 1 b. 2 c. 10 d. 12

c. 10

The median of a sample will always equal the a. mode b. mean c. 50th percentile d. all of the above answers are correct

c. 50th percentile

The variance of a sample was reported to be 144. The report indicated that = 7200. What has been the sample size? a. 49 b. 50 c. 51 d. 52

c. 51

Refer to Exhibit 3-2. The mean is a. 5 b. 6 c. 7 d. 8

c. 7

Which of the following symbols represents the size of the population? a. 2 b. c. d. N

d. N

Which of the following symbols represents the mean of the population? a. 2 b. c. d.

Given the following information: Standard deviation = 8 Coefficient of variation = 64% The mean would then be a. 12.5 b. 8 c. 0.64 d. 1.25

a. 12.5

Refer to Exhibit 3-2. The mode is a. 5 b. 6 c. 7 d. 8

a. 5

Refer to Exhibit 3-6. The range is a. 7 b. 8 c. 9 d. 91

a. 7

Refer to Exhibit 3-6. The mode is a. 84 b. 85 c. 86 d. 87

a. 84

The variance of the sample a. can never be negative b. can be negative c. cannot be zero d. cannot be less than one

a. can never be negative

is an example of a a. population parameter b. sample statistic c. population variance d. mode

a. population parameter

If the variance of a data set is correctly computed with the formula using n - 1 in the denominator, which of the following is true? a. the data set is a sample b. the data set is a population c. the data set could be either a sample or a population d. the data set is from a census

a. the data set is a sample

The symbol 2 is used to represent a. the variance of the population b. the standard deviation of the sample c. the standard deviation of the population d. the variance of the sample

a. the variance of the population

Which of the following symbols represents the standard deviation of the population? a. 2 b. c. d.

The coefficient of correlation ranges between a. 0 and 1 b. -1 and +1 c. minus infinity and plus infinity d. 1 and 100

b. -1 and +1

The weights (in pounds) of a sample of 36 individuals were recorded and the following statistics were calculated. mean = 160 range = 60 mode = 165 variance = 324 median = 170 The coefficient of variation equals a. 0.1125% b. 11.25% c. 203.12% d. 0.20312%

b. 11.25%

Refer to Exhibit 3-3. The interquartile range is a. 1 b. 2 c. 10 d. 12

b. 2

Refer to Exhibit 3-5. The coefficient of variation is a. 25% b. 21.91% c. 5.477% d. 30%

b. 21.91%

Refer to Exhibit 3-3. The standard deviation is a. 8.944 b. 4.062 c. 13.2 d. 16.5

b. 4.062

Refer to Exhibit 3-2. The median is a. 5 b. 6 c. 7 d. 8

b. 6

Refer to Exhibit 3-4. The standard deviation is a. 6.969 b. 7.071 c. 48.570 d. 50.000

b. 7.071

Refer to Exhibit 3-6. The variance is a. 2.828 b. 8 c. 9 d. 81

b. 8

Refer to Exhibit 3-3. The coefficient of variation is a. 72.66% b. 81.24% c. 264% d. 330%

b. 81.24%

A numerical measure of linear association between two variables is the a. variance b. covariance c. standard deviation d. coefficient of variation

b. covariance

80. Refer to Exhibit 3-1. The class width for this distribution a. is 9 b. is 10 c. is 11 d. varies from class to class

b. is 10

The mean of a sample a. is always equal to the mean of the population b. is always smaller than the mean of the population c. is computed by summing the data values and dividing the sum by (n - 1) d. is computed by summing all the data values and dividing the sum by the number of items

b. is always smaller than the mean of the population

The first quartile a. contains at least one third of the data elements b. is the same as the 25th percentile c. is the same as the 50th percentile d. is the same as the 75th percentile

b. is the same as the 25th percentile

Which of the following provides a measure of central location for the data? a. standard deviation b. mean c. variance d. range

b. mean

The 50th percentile is the a. mode b. median c. mean d. third quartile

b. median

The value which has half of the observations above it and half the observations below it is called the a. range b. median c. mean d. mode

b. median

The most frequently occurring value of a data set is called the a. range b. mode c. mean d. median

b. mode

During a cold winter, the temperature stayed below zero for ten days (ranging from -20 to -5). The variance of the temperatures of the ten-day period a. is negative since all the numbers are negative b. must be at least zero c. cannot be computed since all the numbers are negative d. can be either negative or positive

b. must be at least zero

When should measures of location and dispersion be computed from grouped data rather than from individual data values? a. as much as possible since computations are easier b. only when individual data values are unavailable c. whenever computer packages for descriptive statistics are unavailable d. only when the data are from a population

b. only when individual data values are unavailable

Which of the following is not a measure of dispersion? a. the range b. the 50th percentile c. the standard deviation d. the interquartile range

b. the 50th percentile

The coefficient of variation is a. the same as the variance b. the standard deviation divided by the mean times 100 c. the square of the standard deviation d. the mean divided by the standard deviation

b. the standard deviation divided by the mean times 100

The variance of a sample of 81 observations equals 64. The standard deviation of the sample equals a. 9 b. 4096 c. 8 d. 6561

c. 8

Since the population size is always larger than the sample size, then the sample statistic a. can never be larger than the population parameter b. can never be equal to the population parameter c. can be smaller, larger, or equal to the population parameter d. can never be smaller than the population parameter

c. can be smaller, larger, or equal to the population parameter

The coefficient of correlation a. is the same as the coefficient of determination b. can be larger than 1 c. cannot be larger than 1 d. cannot be negative

c. cannot be larger than 1

The median is a measure of a. relative dispersion b. absolute dispersion c. central location d. relative location

c. central location

A numerical measure of linear association between two variables is the a. variance b. coefficient of variation c. correlation coefficient d. standard deviation

c. correlation coefficient

The sample variance a. is always smaller than the true value of the population variance b. is always larger than the true value of the population variance c. could be smaller, equal to, or larger than the true value of the population variance d. can never be zero

c. could be smaller, equal to, or larger than the true value of the population variance

Which of the following is a measure of dispersion? a. percentiles b. quartiles c. interquartile range d. all of the above are measures of dispersion

c. interquartile range

Refer to Exhibit 3-1. The cumulative relative frequency for the class of 10 - 19 a. is 90 b. is .25 c. is .45 d. cannot be determined from the information given

c. is .45

Refer to Exhibit 3-1. The number of students working 19 hours or less a. is 40 b. is 50 c. is 90 d. cannot be determined without the original data

c. is 90

The numerical value of the standard deviation can never be a. larger than the variance b. zero c. negative d. smaller than the variance

c. negative

The variance can never be a. zero b. larger than the standard deviation c. negative d. smaller than the standard deviation

c. negative

Which of the following symbols represents the mean of the sample? a. 2 b. c. d.

Refer to Exhibit 3-3. The variance is a. 80 b. 4.062 c. 13.2 d. 16.5

d. 16.5

The standard deviation of a sample was reported to be 20. The report indicated that = 7200. What has been the sample size? a. 16 b. 17 c. 18 d. 19

d. 19

A group of students had dinner at a local restaurant. The total bill for the dinner was $414.70. Each student paid his/her equal share of the bill, which was $18.85. How many student's were at the dinner? a. 4 b. 415 c. 19 d. 22

d. 22

Refer to Exhibit 3-5. The mean is a. 500 b. 26.315 c. 30 d. 25

d. 25

Refer to Exhibit 3-5. The variance is a. 570 b. 5.477 c. 500 d. 30

d. 30

The standard deviation of a sample of 100 observations equals 64. The variance of the sample equals a. 8 b. 10 c. 6400 d. 4,096

d. 4,096

The heights (in inches) of 25 individuals were recorded and the following statistics were calculated mean = 70 range = 20 mode = 73 variance = 784 median = 74 The coefficient of variation equals a. 11.2% b. 1120% c. 0.4% d. 40%

d. 40%

Refer to Exhibit 3-4. The variance is a. 6.969 b. 7.071 c. 48.570 d. 50.000

d. 50.000

The hourly wages of a sample of 130 system analysts are given below. mean = 60 range = 20 mode = 73 variance = 324 median = 74 The coefficient of variation equals a. 0.30% b. 30% c. 5.4% d. 54%

d. 54%

Refer to Exhibit 3-4. The mean is a. 35 b. 670 c. 10 d. 67

d. 67

If the coefficient of variation is 40% and the mean is 70, then the variance is a. 28 b. 2800 c. 1.75 d. 784

d. 784

Refer to Exhibit 3-2. The 75th percentile is a. 5 b. 6 c. 7 d. 8

d. 8

Refer to Exhibit 3-6. The mean is a. 84 b. 85 c. 86 d. 87

d. 87

Refer to Exhibit 3-6. The median is a. 84 b. 85 c. 86 d. 87

d. 87

From a population of size 400, a random sample of 40 items is selected. The median of the sample a. must be 200, since 400 divided by 2 is 200 b. must be 10, since 400 divided by 400 is 10 c. must be equal to the median of population, if the sample is truly random d. None of these alternatives is correct.