Q69.The mean and standard deviation of 10 observations are 20 and 8 respectively. Later on, it was observed that one observation was recorded as 50 instead of 40. Then the correct variance is (1) 11 (2) 13 (3) 12 (4) 14
What This Question Tests
This problem involves correcting the variance and mean when an observation is wrongly recorded. It requires careful recalculation of the sum of observations and the sum of squares of observations.
Concepts Tested
Formulas Used
Mean X̄ = Σxi / n
Variance σ² = (Σxi² / n) - (X̄)²
Corrected Σxi, Corrected Σxi²
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📋 Question Details
- Chapter
- Statistics
- Topic
- Mean and variance of grouped data
- Year
- 2023
- Shift
- 15 Apr Shift 1
- Q Number
- Q69
- Type
- MCQ
- NCERT Ref
- Class 11 Mathematics Ch 15: Statistics
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