Question:
If the mean of the data : 7, 8, 9, 7, 8, 7, \(\lambda\), 8 is 8, then the variance of this data is :
If the mean of the data : 7, 8, 9, 7, 8, 7, \(\lambda\), 8 is 8, then the variance of this data is :
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Use the given mean to find \(\lambda\), then compute the mean of squared deviations from the mean.
Updated On: Nov 11, 2026
- \(\frac{7}{8}\)
- 1
- \(\frac{9}{8}\)
- 2
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The Correct Option is B
Solution and Explanation
There are 8 observations and the mean is 8, so the sum is 64.
Sum of the known values = 7+8+9+7+8+7+8 = 54, hence \(54+\lambda=64\Rightarrow \lambda=10\).
Deviations from the mean 8: -1, 0, 1, -1, 0, -1, 2, 0.
Squares: 1, 0, 1, 1, 0, 1, 4, 0, sum = 8.
Variance = 8/8 = 1.
Answer: (2) 1
Sum of the known values = 7+8+9+7+8+7+8 = 54, hence \(54+\lambda=64\Rightarrow \lambda=10\).
Deviations from the mean 8: -1, 0, 1, -1, 0, -1, 2, 0.
Squares: 1, 0, 1, 1, 0, 1, 4, 0, sum = 8.
Variance = 8/8 = 1.
Answer: (2) 1
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