Question 1

A researcher wants to know the average amount of time college students spend on social media per day. She surveys 200 students at her university. In this context, what is the population?

Accepted Answer

All college students at her university

Question 2

A study reports that 60% of a sample of 500 city residents support a new recycling program. 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 randomly assigns 100 patients to receive either a new drug or a placebo and measures their blood pressure after 6 weeks. What type of study is this?

Accepted Answer

Experiment

Question 5

A researcher divides a city into 10 neighborhoods, randomly selects 2 neighborhoods, and surveys all residents in those neighborhoods. What sampling technique is used?

Accepted Answer

Cluster 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

A frequency distribution is constructed for the number of pets owned by 30 students. Which graphical display would best show the cumulative totals?

Accepted Answer

Ogive

Question 8

Which of the following best describes a Pareto chart?

Accepted Answer

A bar graph displaying qualitative data in descending order of frequency

Question 9

Given the data set: 3, 7, 7, 9, 10, what is the mode?

Accepted Answer

7

Question 10

The heights (in cm) of five plants are: 12, 15, 15, 18, 20. What is the range?

Accepted Answer

$$ 20 - 12 = 8 $$

Question 11

A data set has a mean of 50 and a standard deviation of 5. According to the Empirical Rule, approximately what percentage of data falls between 45 and 55?

Accepted Answer

68%

Question 12

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 13

A teacher records the test scores of her class: 70, 75, 80, 85, 90. What is the median score?

Accepted Answer

80

Question 14

A company wants to estimate the average commute time of its employees. It selects every 10th employee from an alphabetical list. What sampling method is this?

Accepted Answer

Systematic sampling

Question 15

Which of the following is a potential source of bias in a survey?

Accepted Answer

Surveying only people who are available in the cafeteria at noon

Question 16

Given the grouped data: Class intervals 10-19 (frequency 2), 20-29 (frequency 5), 30-39 (frequency 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 researcher wants to compare the average test scores of students from different majors. She randomly selects 10 students from each major. What sampling technique is this?

Accepted Answer

Stratified sampling

Question 19

Which of the following best describes the difference between a parameter and a statistic?

Accepted Answer

A parameter describes a population, while a statistic describes a sample.

Question 20

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

Accepted Answer

95%

Essential Concepts and Formulas for Introductory Statistics

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