Math Problem Statement

Consider the following sample data set of exam scores, where the sample mean is 83.5 and the sample standard deviation is 16. 1. Use Chebyshev's Rule to determine the minimum percentage of values that should lie within three standard deviations of the mean. 2. What percentage of the raw data falls within three standard deviations of the mean?

Solution

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We have a sample data set of exam scores, with a sample mean of 83.5 and a standard deviation of 16. There are two main questions based on Chebyshev's Rule:

1. Use Chebyshev's Rule to determine the minimum percentage of values that should lie within three standard deviations of the mean.

Chebyshev's Rule states that for any distribution, at least 1k2\frac{1}{k^2} of the data will lie within kk standard deviations of the mean, where kk is any number greater than 1.

For k=3k = 3: 132=19\frac{1}{3^2} = \frac{1}{9} This gives: 119=890.88891 - \frac{1}{9} = \frac{8}{9} \approx 0.8889 So, at least 88.89% of the data should lie within 3 standard deviations of the mean.

2. What percentage of the raw data falls within three standard deviations of the mean?

Now, we need to calculate the range covered by three standard deviations:

  • Mean = 83.5
  • Standard deviation = 16
  • Three standard deviations = 3×16=483 \times 16 = 48

The range within three standard deviations is: 83.548=35.5to83.5+48=131.583.5 - 48 = 35.5 \quad \text{to} \quad 83.5 + 48 = 131.5 Now, we count how many data points fall within this range. The data set is:

92,56,83,48,99,73,79,81,93,92,96,89,88,97,90,91,94,85,92,10092, 56, 83, 48, 99, 73, 79, 81, 93, 92, 96, 89, 88, 97, 90, 91, 94, 85, 92, 100

Every data point lies between 35.5 and 131.5, so 100% of the data falls within three standard deviations of the mean.

Thus, the answer to the second question is 100%.

Would you like further clarifications, or more details?

Here are 5 related questions to extend your understanding:

  1. How does Chebyshev's Rule differ from the Empirical Rule?
  2. Can Chebyshev’s Rule be applied to non-normal distributions?
  3. How do we calculate the percentage for k=2k = 2 standard deviations using Chebyshev’s Rule?
  4. What is the significance of knowing the range of three standard deviations from the mean?
  5. How would the calculation change if the sample mean or standard deviation were different?

Tip: Chebyshev’s Rule is versatile and can be used for any distribution, regardless of its shape.

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Math Problem Analysis

Mathematical Concepts

Statistics
Chebyshev's Inequality
Standard Deviation

Formulas

Chebyshev's Rule: 1 - (1/k^2)
Range within k standard deviations: Mean ± k × Standard Deviation

Theorems

Chebyshev's Inequality

Suitable Grade Level

Grades 10-12