Table of contents
- 1. Intro to Stats and Collecting Data55m
- 2. Describing Data with Tables and Graphs1h 55m
- 3. Describing Data Numerically1h 45m
- 4. Probability2h 16m
- 5. Binomial Distribution & Discrete Random Variables2h 33m
- 6. Normal Distribution and Continuous Random Variables1h 38m
- 7. Sampling Distributions & Confidence Intervals: Mean1h 3m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 12m
- 9. Hypothesis Testing for One Sample1h 1m
- 10. Hypothesis Testing for Two Samples2h 8m
- 11. Correlation48m
- 12. Regression1h 4m
- 13. Chi-Square Tests & Goodness of Fit1h 20m
- 14. ANOVA1h 0m
3. Describing Data Numerically
Standard Deviation
Problem 2.2.54a
Textbook Question
Shifting Data Sample annual salaries (in thousands of dollars) for employees at a company are listed.
40 35 49 53 38 39 40
37 49 34 38 43 47 35
a. Find the sample mean and the sample standard deviation.

1
Step 1: Calculate the sample mean. The sample mean is the average of the data points. Use the formula: , where is the sum of all data points and is the number of data points.
Step 2: Add all the data points together to find . The data points are: 40, 35, 49, 53, 38, 39, 40, 37, 49, 34, 38, 43, 47, 35.
Step 3: Divide the sum of the data points by the total number of data points () to calculate the sample mean.
Step 4: Calculate the sample standard deviation using the formula: . Subtract the sample mean from each data point, square the result, and sum these squared differences.
Step 5: Divide the sum of squared differences by (degrees of freedom), then take the square root of the result to find the sample standard deviation.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Sample Mean
The sample mean is the average of a set of values, calculated by summing all the data points and dividing by the number of points. It provides a central value that represents the data set, making it easier to understand the overall trend. In this case, it helps summarize the annual salaries of employees at the company.
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Sample Standard Deviation
The sample standard deviation measures the amount of variation or dispersion in a set of values. It indicates how much individual data points differ from the sample mean. A low standard deviation suggests that the data points are close to the mean, while a high standard deviation indicates greater variability among the salaries.
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Data Shifting
Data shifting refers to the process of adjusting the values in a data set, often to analyze the effects of changes in the data. In the context of this question, understanding how to calculate the mean and standard deviation after shifting the data can provide insights into how such adjustments impact the overall statistics of the salaries.
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