Question 1

Which of the following best describes the difference between a population and a sample in statistics?

Accepted Answer

A population includes all individuals of interest, while a sample is a subset selected from the population.

Question 2

A researcher wants to estimate the average commute time for all employees at a company. She randomly selects 30 employees and records their commute times. In this context, what is the statistic?

Accepted Answer

The average commute time of the 30 selected employees.

Question 3

Which of the following is an example of a categorical (qualitative) variable?

Accepted Answer

Your favorite color.

Question 4

A survey asks respondents to rate their satisfaction on a scale: Poor, Fair, Good, Excellent. What level of measurement is this?

Accepted Answer

Ordinal

Question 5

Which sampling method is most likely to produce a biased sample?

Accepted Answer

Convenience sampling

Question 6

Given the following 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 has class boundaries 10-19, 20-29, 30-39. What is the class width?

Accepted Answer

$$ 10 $$

Question 8

Which of the following is NOT a potential pitfall in statistical studies?

Accepted Answer

Random sampling

Question 9

If the mean number of chocolate chips in a cookie is 23.5 with a standard deviation of 1.91, what is the range of values that are NOT statistically significant (within 2 standard deviations)?

Accepted Answer

$$ 23.5 \pm 3.82 $$

Question 10

A histogram is used to display which type of data?

Accepted Answer

Quantitative data

Question 11

Which formula correctly calculates the sample variance $$ s^2$ $$ for a data set $$ x_1$, x_2$, ..., x_n $$?

Accepted Answer

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

Question 12

If a value is in the 90th percentile, what does this mean?

Accepted Answer

It is higher than 90% of the data.

Question 13

A boxplot is useful for displaying which of the following?

Accepted Answer

The 5-number summary (minimum, Q1, median, Q3, maximum)

Question 14

Which of the following is a correct interpretation of a z-score of $$ z = 2 $$?

Accepted Answer

The value is 2 standard deviations above the mean.

Question 15

Which of the following is an example of a systematic sample?

Accepted Answer

Selecting every 5th student from a list of all students.

Question 16

Given the data set: 2, 4, 6, 8, 10, what is the median?

Accepted Answer

$$ 6 $$

Question 17

Which of the following best describes the midrange of a data set?

Accepted Answer

The average of the maximum and minimum values.

Question 18

A pie chart is most appropriate for displaying:

Accepted Answer

The distribution of a categorical variable.

Question 19

If a data set is highly skewed to the right, which measure of center is most affected?

Accepted Answer

Mean

Statistics Unit 1: Introduction, Data Exploration, and Descriptive Statistics

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