STATS EXAM 1

In constructing a frequency distribution, the approximate class interval is computed as A) (maximum value − minimum value)/(number of classes). B) (maximum value − minimum value)/(sample size). C) (minimum value − maximum value)/(sample size). D) (maximum value)/(number of classes − sample size).

A) (maximum value − minimum value)/(number of classes).

Refer to the following frequency distribution of days absent during a calendar year by employees of a manufacturing company: Days Absent: Number of Employees: 0 up to 3 60 3 up to 6 31 6 up to 9 14 9 up to 12 6 12 up to 15 2 How many employees were absent for 3 up to 6 days? A) 31 B) 29 C) 14 D) 2

A) 31

The Equal Employment Opportunity Act requires employers to classify their employees by gender and national origin. Which level of measurement is this? A) Nominal B) Ordinal C) Interval D) Ratio

A) Nominal

What statistics are needed to draw a box plot? A) The minimum, maximum, median, first and third quartiles B) The median, mean, and standard deviation C) The median and interquartile range D) The mean and standard deviation

A) The minimum, maximum, median, first and third quartiles

When data are collected using a qualitative, nominal variable, what is true about a frequency table that summarizes the data? A) The upper and lower class limits must be calculated. B) A pie chart can be used to summarize the data. C) The number of classes is equal to the number of variable's values plus 2. D) The "5 to the k rule" can be applied.

A) The upper and lower class limits must be calculated.

The main purpose of descriptive statistics is to A) summarize data in a useful and informative manner. B) make inferences about a population. C) determine if the data adequately represent the population. D) gather or collect data.

A) summarize data in a useful and informative manner.

The monthly salaries of a sample of 100 employees were rounded to the nearest $10. They ranged from a low of $1,040 to a high of $1,720. If we want to condense the data into seven classes, what is the most convenient class interval? A) $50 B) $100 C) $150 D) $200

B) $100

The variance of a sample of 121 observations equals 441. The standard deviation of the sample equals A) 11. B) 21. C) 1.91. D) 231.

B) 21.

Using the following statistics to describe a distribution of data, what is the interquartile range? Minimum = 10 Q1 = 25 Median = 50 Q3 = 75 Maximum = 95 A) 85 B) 50 C) 15 D) 20

B) 50

40) The sum of the deviations of each data value from this measure of central location will always be zero. A) Mode B) Mean C) Median D) Standard deviation

B) Mean

A student was interested in the cigarette-smoking habits of college students and collected data from an unbiased random sample of students. The data are summarized in the following table: Males 50 Females 75 Males who smoke 20 Males who do not smoke 30 Females who smoke 25 Females who do not smoke 50 What is wrong with this frequency table? A) The number of males does not equal the sum of males that smoke and do not smoke. B) The classes are not mutually exclusive. C) There are too many classes. D) Class limits cannot be computed.

B) The classes are not mutually exclusive.

Sometimes, a data set has two values that have the highest and equal frequencies. In this case, the distribution of the data can best be described as ________. A) symmetric B) bimodal (having two modes) C) positively skewed D) negatively skewed

B) bimodal (having two modes)

In a distribution, the second quartile corresponds with the ________. A) mean B) median C) mode D) variance

B) median

Monthly commissions of first-year insurance brokers are $1,270, $1,310, $1,680, $1,380, $1,410, $1,570, $1,180, and $1,420. These figures are referred to as A) a histogram. B) raw data. C) a frequency distribution. D) a frequency polygon.

B) raw data.

A portion or part of a population is called a A) random survey. B) sample. C) tally. D) frequency distribution.

B) sample.

If the coefficient of skewness is equal to zero, the shape of the distribution is ________. A) negatively skewed B) symmetric C) positively skewed D) unknown

B) symmetric

For a sample of similar-sized all-electric homes, the March electric bills were (to the nearest dollar): $212, $191, $176, $129, $106, $92, $108, $109, $103, $121, $175, and $194. What is the range? A) $100 B) $130 C) $120 D) $112

C) $120

For a data set with an odd number of observations that have been sorted from smallest to largest values, where is the median located? A) n B) n/2 C) (n + 1)/2 D) n + 1/2

C) (n + 1)/2

Refer to the following distribution of ages: Ages Frequency 40 up to 50 10 50 up to 60 28 60 up to 70 12 For this distribution of ages, what is the relative class frequency for the lowest class? A) 0.50 B) 0.18 C) 0.20 D) 0.10

C) 0.20

Refer to the following breakdown of responses to a survey of "Are you concerned about being tracked while connected to the Internet?" Response Frequency Very Concerned 140 Somewhat Concerned 40 No Concern 20 What percentage of the responses indicated that users were somewhat concerned? A) 40% B) 70% C) 20% D) 100%

C) 20%

In the following set of data: (1, 3, 5, 6, 7, 9, 100), what are the first, second, and third quartiles? A) 1, 6, and 100 B) 3, 5, and 9 C) 3, 6, and 9 D) 1, 5, and 100

C) 3, 6, and 9

According to Chebyshev's theorem, at least what percent of the observations lie within plus and minus 1.75 standard deviations of the mean? A) 56% B) 95% C) 67% D) 100%

C) 67%

Which measures of central location are not affected by extremely small or extremely large values? A) Mean and median B) Mean and mode C) Mode and median D) Standard deviation and mean

C) Mode and median

Which of the following is NOT a measure of dispersion? A) The interquartile range B) The standard deviation C) The 50th percentile D) The range

C) The 50th percentile

Outliers are clearly presented in a ________. A) dot plot B) stem-and-leaf display C) box plot D) contingency table

C) box plot

Income is a variable often used in business and economics. Income is an example of a variable that uses the A) ordinal scale. B) nominal scale. C) ratio scale. D) interval scale.

C) ratio scale.

A dot plot can be used to show ________. A) the mean, median, and mode B) the general shape of a distribution for a nominal qualitative variable C) the distribution for a quantitative variable D) the interquartile range

C) the distribution for a quantitative variable

The 67th percentile is ________. A) the value above which 67% of the observations occur B) a value one less than 67% of the observations C) the value below which 67% of the observations occur D) the value of the observation at the 67th location

C) the value below which 67% of the observations occur

The monthly amounts spent for food by families of four receiving food stamps approximates a symmetrical, normal distribution. The sample mean is $150 and the standard deviation is $20. Using the Empirical rule, about 95% of the monthly food expenditures are between what two amounts? A) $100 and $200 B) $85 and $105 C) $205 and $220 D) $110 and $190

D) $110 and $190

Here is a sample distribution of hourly earnings in Paul's Cookie Factory: Hourly Earning $6 up to $9 $9 up to $12 $12 up to $15 Frequency 16 42 10 The limits of the class with the smallest frequency are A) $6.00 and $9.00. B) $12.00 and up to $14.00. C) $11.75 and $14.25. D) $12.00 and up to $15.00.

D) $12.00 and up to $15.00.

A sample of experienced typists revealed that their mean typing speed is 87 words per minute and the median typing speed is 73 words per minute. The standard deviation of typing speed is 16.9 words per minute. What is the Pearson coefficient of skewness? A) −2.5 B) −4.2 C) +4.2 D) +2.5

D) +2.5

A sample of small bottles and their contents has the following weights (in grams): 4, 2, 5, 4, 5, 2, and 6. What is the sample variance of bottle weight? A) 6.92 B) 4.80 C) 1.96 D) 2.33

D) 2.33

Refer to the following distribution of ages: Ages Frequency 40 up to 50 10 50 up to 60 28 60 up to 70 12 What is the class midpoint of the highest class? A) 54 B) 55 C) 64 D) 65

D) 65

A survey includes a question about marital status that has the following responses: single, married, divorced, separated, or widowed. What is the scale of measurement for this question? A) Ratio B) Interval C) Ordinal D) Nominal

D) Nominal

What level of measurement is a person's "favorite sport"? A) Ratio B) Ordinal C) Interval D) Nominal

D) Nominal

Which word is NOT part of the definition of descriptive statistics? A) Organizing B) Summarizing C) Presenting D) Predicting

D) Predicting

The incomes of 50 loan applicants are obtained. Which level of measurement is income? A) Nominal B) Ordinal C) Interval D) Ratio

D) Ratio

Consider two populations with the same mean. Since they have the same mean, then A) their standard deviations must also be the same. B) their medians must also be the same. C) their modes must also be the same. D) none of these is correct.

D) none of these is correct.

The relative frequency for a class represents the A) class width. B) class midpoint. C) class interval. D) percentage of observations in the class.

D) percentage of observations in the class.

True or False: A dot plot is useful for quickly graphing frequencies in a small data set

False

True or False: A frequency table for qualitative data has class limits.

False

True or False: A listing of 100 family annual incomes is an example of statistics.

False

True or False: A set of ordinal-, interval-, or ratio-level data may have only one mode.

False

True or False: A store asks shoppers for their zip codes to identify market areas. Zip codes are an example of ratio data.

False

True or False: A student scored in the 85th percentile on a standardized test. This means that the student scored lower than 85% of all students who took the test

False

True or False: Extremely high or low scores affect the value of the median.

False

True or False: In a company, the standard deviation of the ages of female employees is 6 years and the standard deviation of the ages of male employees is 10 years. These statistics indicate that the dispersion of age is greater for females than for males.

False

True or False: Quartiles divide a distribution into 10 equal parts.

False

True or False: There are four levels of measurement: qualitative, quantitative, discrete, and continuous.

False

True or False: A dot plot is useful for showing the range of the data.

True

True or False: A marketing research agency was hired to test a new DVD player. Consumers rated it outstanding, very good, fair, or poor. The level of measurement for this experiment is ordinal.

True

True or False: A population is a collection of all individuals, objects, or measurements of interest.

True

True or False: Data measured on a nominal scale can only be classified into categories.

True

True or False: If a distribution is negatively skewed, the distribution is not symmetrical and the long tail is to the left.

True

True or False: In a bar chart, the horizontal axis is usually labeled with the values of a qualitative variable.

True

True or False: In frequency distributions, classes are mutually exclusive if each individual, object, or measurement is included in only one category.

True

True or False: Statistics is used to report the summary results of market surveys.

True

True or False: The arithmetic mean is the sum of the quantitative observations divided by the total number of observations.

True

True or False: To convert a frequency distribution to a relative frequency distribution, divide each class frequency by the sum of the class frequencies.

True

True or False: To infer something about a population, we usually take a sample from the population.

True

True or False: Variation describes the degree of dispersion in the data.

True

True or False:A scatter diagram of sales versus production is labeled with sales on the Y-axis and production on the X-axis.

True