Math Problem Statement

Find the standard deviation for the group of data items using the stem-and-leaf plot.

Solution

To calculate the standard deviation for this data:

Step 1: Extract the data

The stem-and-leaf plot represents:

  • Stem 0 with leaf 6 = 6
  • Stem 1 with leaves 1, 6 = 11, 16
  • Stem 2 with leaves 1, 6 = 21, 26

The data set is:
6,11,16,21,266, 11, 16, 21, 26

Step 2: Calculate the mean

Mean=Sum of dataNumber of data points=6+11+16+21+265=805=16\text{Mean} = \frac{\text{Sum of data}}{\text{Number of data points}} = \frac{6 + 11 + 16 + 21 + 26}{5} = \frac{80}{5} = 16

Step 3: Calculate the squared differences from the mean

For each data point: (616)2=(10)2=100(6 - 16)^2 = (-10)^2 = 100 (1116)2=(5)2=25(11 - 16)^2 = (-5)^2 = 25 (1616)2=02=0(16 - 16)^2 = 0^2 = 0 (2116)2=52=25(21 - 16)^2 = 5^2 = 25 (2616)2=102=100(26 - 16)^2 = 10^2 = 100

Step 4: Find the variance

The variance is the average of these squared differences: Variance=Sum of squared differencesNumber of data points=100+25+0+25+1005=2505=50\text{Variance} = \frac{\text{Sum of squared differences}}{\text{Number of data points}} = \frac{100 + 25 + 0 + 25 + 100}{5} = \frac{250}{5} = 50

Step 5: Find the standard deviation

The standard deviation is the square root of the variance: Standard Deviation=507.07\text{Standard Deviation} = \sqrt{50} \approx 7.07

Final Answer:

Standard Deviation=7.07\text{Standard Deviation} = 7.07

Would you like further clarification or additional examples?


Relative Questions:

  1. How is variance related to standard deviation?
  2. How do you interpret the standard deviation value in this context?
  3. What changes if you calculate a sample standard deviation instead of a population standard deviation?
  4. Can you compare this result to a different dataset with a higher mean but similar deviation?
  5. How would adding an extreme outlier affect the standard deviation?

Tip: The standard deviation provides insight into the data's spread around the mean—smaller values indicate tighter clustering.

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Math Problem Analysis

Mathematical Concepts

Statistics
Standard Deviation
Variance

Formulas

Mean = (Sum of data points) / (Number of data points)
Variance = (Sum of squared differences from the mean) / (Number of data points)
Standard Deviation = √Variance

Theorems

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Suitable Grade Level

Grades 9-12