Math Problem Statement
The mean and sample standard deviation of the dataset consisting of 9 observations is 14 and 10 respectively. Later it is noted that one observation 11 is wrongly noted as 6. What is the sample variance of the original dataset? (Correct to 2 decimal place accuracy)
Solution
To find the sample variance of the original dataset, we need to correct the mistakenly recorded value and then recalculate the variance.
Given:
- Mean () of the dataset: 14
- Sample standard deviation (s): 10
- Number of observations (n): 9
- Incorrect value: 6 (should be 11)
First, let's determine the sum of the original dataset using the mean:
Now, let's find the sum of squares of the original dataset using the variance formula:
Next, we need to adjust this sum of squares to account for the incorrect value:
The incorrect dataset sum of squares can be expressed as:
Identify and correct the contribution of the incorrect value:
- Incorrect value: 6
- Correct value: 11
The difference in the squares due to the correction is:
The corrected sum of squares:
Recalculate the sample variance with the corrected sum of squares:
Thus, the sample variance of the original dataset, corrected to two decimal places, is:
Would you like further details or have any questions? Here are some related questions you might find useful:
- How do you calculate the sample mean from a dataset?
- What is the difference between sample variance and population variance?
- How do you find the sum of squares in a dataset?
- What steps are involved in correcting a dataset with an error?
- How do changes in individual data points affect the overall variance?
Tip: Always double-check your dataset for accuracy before performing statistical calculations to ensure valid results.
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Math Problem Analysis
Mathematical Concepts
Statistics
Sample Variance
Standard Deviation
Formulas
Sample Variance Formula
Standard Deviation Formula
Theorems
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Suitable Grade Level
Advanced High School
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