Math Problem Statement

Scenario: Imagine tracking the number of hours spent studying per week by students in a class: 5, 7, 10, 8, 6, 9, 4, 12, 8, 6. Now, Identify and compute the appropriate measure of dispersion using the step-by-step process.

Solution

To compute the measure of dispersion for the given dataset of hours spent studying, we'll calculate the standard deviation step by step. Standard deviation is a common measure that tells us how spread out the data points are relative to the mean. Here’s the step-by-step process:

1. Data Set:

The study hours per week are:
5,7,10,8,6,9,4,12,8,65, 7, 10, 8, 6, 9, 4, 12, 8, 6

2. Calculate the Mean:

First, we need to compute the mean (μ\mu) of the data.

μ=Data ValuesNumber of Values=5+7+10+8+6+9+4+12+8+610=7510=7.5\mu = \frac{\sum \text{Data Values}}{\text{Number of Values}} = \frac{5 + 7 + 10 + 8 + 6 + 9 + 4 + 12 + 8 + 6}{10} = \frac{75}{10} = 7.5

The mean study hours per week is 7.5 hours.

3. Find the Deviations:

Next, calculate how far each value is from the mean (deviation):

  • 57.5=2.55 - 7.5 = -2.5
  • 77.5=0.57 - 7.5 = -0.5
  • 107.5=2.510 - 7.5 = 2.5
  • 87.5=0.58 - 7.5 = 0.5
  • 67.5=1.56 - 7.5 = -1.5
  • 97.5=1.59 - 7.5 = 1.5
  • 47.5=3.54 - 7.5 = -3.5
  • 127.5=4.512 - 7.5 = 4.5
  • 87.5=0.58 - 7.5 = 0.5
  • 67.5=1.56 - 7.5 = -1.5

4. Square Each Deviation:

Now, square each of the deviations:

  • (2.5)2=6.25(-2.5)^2 = 6.25
  • (0.5)2=0.25(-0.5)^2 = 0.25
  • (2.5)2=6.25(2.5)^2 = 6.25
  • (0.5)2=0.25(0.5)^2 = 0.25
  • (1.5)2=2.25(-1.5)^2 = 2.25
  • (1.5)2=2.25(1.5)^2 = 2.25
  • (3.5)2=12.25(-3.5)^2 = 12.25
  • (4.5)2=20.25(4.5)^2 = 20.25
  • (0.5)2=0.25(0.5)^2 = 0.25
  • (1.5)2=2.25(-1.5)^2 = 2.25

5. Sum the Squared Deviations:

Add up all the squared deviations:

6.25+0.25+6.25+0.25+2.25+2.25+12.25+20.25+0.25+2.25=52.56.25 + 0.25 + 6.25 + 0.25 + 2.25 + 2.25 + 12.25 + 20.25 + 0.25 + 2.25 = 52.5

6. Calculate the Variance:

The variance (σ2\sigma^2) is the average of these squared deviations. Since we are calculating for the population (not a sample), we divide by the number of data points:

σ2=52.510=5.25\sigma^2 = \frac{52.5}{10} = 5.25

7. Calculate the Standard Deviation:

Finally, the standard deviation (σ\sigma) is the square root of the variance:

σ=5.252.29\sigma = \sqrt{5.25} \approx 2.29

Conclusion:

The standard deviation of the study hours is approximately 2.29 hours, indicating that the study times typically vary about 2.29 hours from the mean of 7.5 hours.


Would you like more details or have any questions about this process?

Here are five related questions to consider:

  1. How would the process differ if we calculated the standard deviation for a sample instead of a population?
  2. What are other measures of dispersion besides standard deviation?
  3. How does the variance change if one of the study hours is significantly increased?
  4. Can you interpret what a higher or lower standard deviation would imply in this scenario?
  5. How would the median be affected by extreme values compared to the mean?

Tip: Always check whether you're working with a sample or a population, as it affects the divisor in variance and standard deviation calculations.

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Math Problem Analysis

Mathematical Concepts

Statistics
Measure of Dispersion
Standard Deviation

Formulas

Mean: μ = (Σ Data Values) / (Number of Values)
Variance: σ² = Σ(Deviation²) / N
Standard Deviation: σ = √(Variance)

Theorems

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Suitable Grade Level

Grades 9-12