Question 1

A researcher wants to know the average height of all university students in the country. She randomly selects 200 students from her university and calculates their average height. In this scenario, what is the population?

Accepted Answer

All university students in the country

Question 2

A study reports that 60% of a sample of 500 city residents support a new public transportation system. Is the value 60% a parameter or a statistic?

Accepted Answer

Statistic

Question 3

Which of the following is a qualitative variable?

Accepted Answer

Favorite type of cuisine

Question 4

A pharmaceutical company tests a new drug by giving it to one group and a placebo to another, then compares the results. What type of study is this?

Accepted Answer

Experiment

Question 5

A polling organization selects every 10th person from a list of registered voters. What sampling technique is being used?

Accepted Answer

Systematic sampling

Question 6

Given the data set: 2, 4, 4, 6, 8, what is the mean?

Accepted Answer

$$\frac{2+4+4+6+8}{5} = 4.8$$

Question 7

Which of the following best describes a Pareto chart?

Accepted Answer

A bar graph where categories are ordered by frequency from highest to lowest

Question 8

A data set has the following values: 3, 7, 7, 9, 10. What is the mode?

Accepted Answer

7

Question 9

Which formula would you use to calculate the sample variance for a data set?

Accepted Answer

$$s^2$$ = \frac{\sum (x - \overline{x}$$)^2$$}{n-1}$$

Question 10

A bell-shaped distribution has a mean of 100 and a standard deviation of 10. According to the Empirical Rule, what percentage of data falls between 80 and 120?

Accepted Answer

95%

Question 11

A researcher divides a city into neighborhoods and randomly selects 5 neighborhoods, then surveys all residents in those neighborhoods. What sampling method is this?

Accepted Answer

Cluster sampling

Question 12

Given the data set: 5, 8, 12, 15, 20, what is the range?

Accepted Answer

$$20 - 5 = 15$$

Question 13

Which of the following is an example of convenience sampling?

Accepted Answer

Surveying people who happen to be at a shopping mall

Question 14

A cumulative frequency distribution is best represented by which type of graph?

Accepted Answer

Ogive

Question 15

Which of the following is NOT a potential source of bias in sampling?

Accepted Answer

Using a random number generator to select participants

Question 16

Given the following grouped data: Class intervals: 10-19, 20-29, 30-39; Frequencies: 2, 5, 3. What is the midpoint of the class 20-29?

Accepted Answer

$$\frac{20+29}{2} = 24.5$$

Question 17

A stem-and-leaf plot is most useful for which of the following?

Accepted Answer

Displaying the distribution of a small set of quantitative data

Question 18

A hospital administrator wants to compare the average length of stay for patients in different departments. Which measure of central tendency is most appropriate if the data are skewed?

Accepted Answer

Median

Question 19

Which formula would you use to calculate the population variance?

Accepted Answer

$$\$$sigma^2$$ = \frac{\sum (x - \mu)^2$}{N}$$

Question 20

A frequency polygon is constructed by plotting which of the following?

Accepted Answer

Frequencies at the midpoints of each class interval

Core Concepts and Formulas in Descriptive Statistics

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