Math Problem Statement

Find the standard deviation for the group of data items. Stems

Leaves 1 6     2 2

6 3 2

6 Question content area bottom Part 1 The standard deviation is enter your response here . ​(Round to two decimal places as​ needed.)

Solution

To find the standard deviation for the given data, we first extract the actual data values from the stem-and-leaf plot. Here’s how we interpret the data:

Data interpretation from the stem-and-leaf plot:

  • Stems represent the tens place.
  • Leaves represent the units place.

Step 1: List the Data Values

Based on the stem and leaf structure provided:

  • 161 | 6 means 16
  • 222 | 2 and 262 | 6 mean 22 and 26
  • 323 | 2 and 363 | 6 mean 32 and 36

So, the dataset is: 16,22,26,32,3616, 22, 26, 32, 36

Step 2: Calculate the Mean (Average)

The mean μ\mu is calculated as: μ=16+22+26+32+365=1325=26.4\mu = \frac{16 + 22 + 26 + 32 + 36}{5} = \frac{132}{5} = 26.4

Step 3: Calculate Each Value's Deviation from the Mean, Square It, and Find the Average

For each value xx, calculate (xμ)2(x - \mu)^2:

  1. For x=16x = 16: (1626.4)2=(10.4)2=108.16(16 - 26.4)^2 = (-10.4)^2 = 108.16
  2. For x=22x = 22: (2226.4)2=(4.4)2=19.36(22 - 26.4)^2 = (-4.4)^2 = 19.36
  3. For x=26x = 26: (2626.4)2=(0.4)2=0.16(26 - 26.4)^2 = (-0.4)^2 = 0.16
  4. For x=32x = 32: (3226.4)2=(5.6)2=31.36(32 - 26.4)^2 = (5.6)^2 = 31.36
  5. For x=36x = 36: (3626.4)2=(9.6)2=92.16(36 - 26.4)^2 = (9.6)^2 = 92.16

Sum of squared deviations: 108.16+19.36+0.16+31.36+92.16=251.2108.16 + 19.36 + 0.16 + 31.36 + 92.16 = 251.2

Step 4: Find the Variance and Standard Deviation

The variance σ2\sigma^2 is the average of these squared deviations: σ2=251.25=50.24\sigma^2 = \frac{251.2}{5} = 50.24

The standard deviation σ\sigma is the square root of the variance: σ=50.247.09\sigma = \sqrt{50.24} \approx 7.09

Answer

The standard deviation is approximately 7.09.

Would you like further clarification on any step?

Here are some related questions you might find helpful:

  1. How is the variance related to standard deviation?
  2. What is the difference between population and sample standard deviation?
  3. Why do we square the deviations when calculating variance?
  4. How does standard deviation interpret the spread of data?
  5. How would the standard deviation change if more values were added?

Tip: Always double-check your data extraction from stem-and-leaf plots to ensure accurate calculations.

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Math Problem Analysis

Mathematical Concepts

Statistics
Standard Deviation
Variance
Mean

Formulas

Mean: μ = (Σx) / N
Variance: σ^2 = (Σ(x - μ)^2) / N
Standard Deviation: σ = √σ^2

Theorems

Calculation of Variance and Standard Deviation

Suitable Grade Level

Grades 10-12