Q: Which of the following best describes an outlier in a box plot?

A value that falls outside $$Q1 - 1.5 \times IQR or$$ $$Q3 + 1.5 \times IQR$$

Question 1

Which of the following best describes the difference between descriptive and inferential statistics?

Accepted Answer

Descriptive statistics summarize and describe the main features of a dataset, while inferential statistics use sample data to make predictions or inferences about a population.

Question 2

A researcher wants to estimate the average satisfaction rating of all passengers at an airport. She surveys 2,000 passengers and calculates the mean satisfaction rating. In this context, what is the 'parameter'?

Accepted Answer

The mean satisfaction rating of all passengers at the airport.

Question 3

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

Accepted Answer

Favorite color

Question 4

Given the following data set: 2, 3, 4, 4, -6, -7, 0, 9, 5, 9, 9, 10. What is the mode?

Accepted Answer

9

Question 5

Which formula correctly calculates the sample mean $$\bar{y}$$ for $$n$$ observations $$y_1$$, $$y_2$$, ..., y_n$$?

Accepted Answer

$$\bar{y} = \frac{1}{n} \sum_{i=1}^{n} y_i$$

Question 6

A box plot shows a data set with Q1 = 15, Q3 = 22, and an outlier at 33. What is the interquartile range (IQR)?

Accepted Answer

$$IQR = Q3 - Q1 = 22 - 15 = 7$$

Question 7

Which of the following statements about the mean and median is correct?

Accepted Answer

In a symmetric distribution, the mean and median are equal.

Question 8

Which formula is used to calculate the sample variance $$S^2$$ for $$n$$ observations $$y_1$$, $$y_2$$, ..., y_n$$ with sample mean $$\bar{y}$$?

Accepted Answer

$$S^2$$ = \frac{\sum_{i=1}^{n} (y_i - \bar{y}$$)^2$$}{n-1}$$

Question 9

A histogram is most appropriate for displaying which type of data?

Accepted Answer

Quantitative (continuous or discrete) data

Question 10

In the context of the PPDAC cycle, which step involves generating hypotheses and constructing graphs?

Accepted Answer

Analysis

Question 11

If a data set has a minimum value of 10 and a maximum value of 35, what is the range?

Accepted Answer

$$Range = 35 - 10 = 25$$

Question 12

Which of the following is NOT a measure of location?

Accepted Answer

Standard deviation

Question 13

A frequency table for soft drink purchases shows Coca-Cola: 19, Diet Coke: 8, Dr. Pepper: 5, Pepsi: 13, Sprite: 5. What is the proportion of Pepsi purchases?

Accepted Answer

$$\frac{13}{50} = 0.26$$

Question 14

Which of the following best describes an outlier in a box plot?

Accepted Answer

A value that falls outside $$Q1 - 1.5 	imes IQR or$$ $$Q3 + 1.5 	imes IQR$$

Question 15

Which of the following is a correct interpretation of the 25th percentile?

Accepted Answer

25% of the data fall below or at this value.

Question 16

A company wants to know the average time employees spend commuting. They survey 100 employees. What is the 'sample' in this context?

Accepted Answer

The 100 employees surveyed

Question 17

Which of the following is a measure of variability/dispersion?

Accepted Answer

Variance

Question 18

If the sample variance $$S^2 = 11.2$, what is the sample standard deviation S$?

Accepted Answer

$$S = \sqrt{11.2} \approx 3.35$$

Question 19

Which of the following is NOT a step in the PPDAC cycle?

Accepted Answer

Prediction

Exploratory Data Analysis I: One Parameter – Foundations of Business Statistics

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