Math Problem Statement

Find the standard deviation for the following data. Round your answer to 2 decimal places as needed

66

80

29

57

47

8

37

36

Solution

To find the standard deviation, we'll follow these steps:

Step 1: Calculate the mean (average)

The mean is the sum of all the numbers divided by the total count.

Mean=66+80+29+57+47+8+37+368=3608=45\text{Mean} = \frac{66 + 80 + 29 + 57 + 47 + 8 + 37 + 36}{8} = \frac{360}{8} = 45

Step 2: Subtract the mean from each data point and square the result

(6645)2=441(66 - 45)^2 = 441 (8045)2=1225(80 - 45)^2 = 1225 (2945)2=256(29 - 45)^2 = 256 (5745)2=144(57 - 45)^2 = 144 (4745)2=4(47 - 45)^2 = 4 (845)2=1369(8 - 45)^2 = 1369 (3745)2=64(37 - 45)^2 = 64 (3645)2=81(36 - 45)^2 = 81

Step 3: Calculate the variance

The variance is the average of the squared differences. Since this is a sample, we'll divide by n1=81=7n - 1 = 8 - 1 = 7.

Variance=441+1225+256+144+4+1369+64+817=35847=512\text{Variance} = \frac{441 + 1225 + 256 + 144 + 4 + 1369 + 64 + 81}{7} = \frac{3584}{7} = 512

Step 4: Calculate the standard deviation

The standard deviation is the square root of the variance.

Standard Deviation=51222.63\text{Standard Deviation} = \sqrt{512} \approx 22.63

So, the standard deviation is approximately 22.63.

Would you like further details on any step, or have any questions?

Here are 5 relative questions to consider:

  1. How is variance related to standard deviation?
  2. What is the difference between population and sample standard deviation?
  3. Why do we square the differences when calculating variance?
  4. How would the standard deviation change if we added more data points?
  5. Can standard deviation ever be negative?

Tip: Always clarify whether the data represents a sample or the entire population. This affects whether you divide by n1n-1 (sample) or nn (population) when calculating variance.

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Math Problem Analysis

Mathematical Concepts

Statistics
Standard Deviation
Variance
Mean

Formulas

Mean = (Sum of data points) / (Number of data points)
Variance = (Sum of squared differences from the mean) / (n - 1) for a sample
Standard Deviation = Square root of the variance

Theorems

Empirical Rule (68-95-99.7 rule) in statistics
Chebyshev's Theorem (for non-normal distributions)

Suitable Grade Level

Grades 9-12