Question:medium

Marks of 5 students of a group are \( 8, 12, 13, 15, 22 \). Find the variance.

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To find the variance, first calculate the mean, then determine the squared deviations from the mean, and finally divide the sum of these squared deviations by the total number of data points.
Updated On: Nov 26, 2025
  • \( 22.1 \)
  • \( 23.0 \)
  • \( 20.2 \)
  • \( 21.2 \)
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The Correct Option is D

Solution and Explanation

Step 1: Calculate the mean (\( \bar{x} \)) of the dataset. \[ \bar{x} = \frac{\sum x_i}{n} = \frac{8 + 12 + 13 + 15 + 22}{5} = 14. \] Step 2: Determine the squared differences of each data point from the mean. \[ (x_i - \bar{x})^2 = \{(8-14)^2, (12-14)^2, (13-14)^2, (15-14)^2, (22-14)^2\}. \] \[ (x_i - \bar{x})^2 = \{36, 4, 1, 1, 64\}. \] Step 3: Compute the variance. \[ \text{Variance (Var(x))} = \frac{\sum (x_i - \bar{x})^2}{n} = \frac{36 + 4 + 1 + 1 + 64}{5} = \frac{106}{5} = 21.2. \] Final Answer: The variance for the provided data is: \[ \boxed{21.2} \]
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