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 wrongly noted observation and then recalculate the variance. Let's follow the steps:
-
Mean and standard deviation of the incorrect dataset:
- Mean () = 14
- Standard deviation (s) = 10
-
Calculating the sum of the incorrect dataset: Since the mean is the sum of all observations divided by the number of observations ():
-
Identifying the incorrect observation: The incorrect observation is 6, and the correct observation is 11.
-
Sum of the correct dataset: Adjust the sum by replacing 6 with 11:
-
Mean of the correct dataset:
-
Calculating the sum of squares of deviations for the incorrect dataset: The formula for the sample variance is: Therefore:
-
Correcting the sum of squares of deviations: We need to adjust this sum for the corrected observation:
-
Calculating the sample variance for the corrected dataset:
Therefore, the sample variance of the original dataset is approximately .
Would you like any details or have any questions about this process? Here are some related questions you might find useful:
- How do you calculate the sample variance?
- What is the difference between sample variance and population variance?
- How does correcting an observation affect the dataset's mean and variance?
- What is the importance of the mean in a dataset?
- How do you calculate the standard deviation from the variance?
Tip: Always double-check your data for any incorrect entries as even a small error can significantly affect statistical calculations.
Ask a new question for Free
By Image
Drop file here or Click Here to upload
Math Problem Analysis
Mathematical Concepts
Statistics
Descriptive Statistics
Variance
Formulas
Sample Variance formula
Theorems
-
Suitable Grade Level
Undergraduate