Q71.If the mean and variance of eight numbers 3, 7, 9, 12, 13, 20, x and y be 10 and 25 respectively, then x ⋅y is equal to
What This Question Tests
This question tests the student's ability to apply the formulas for mean and variance of ungrouped data, leading to a system of two equations that must be solved algebraically.
Concepts Tested
Formulas Used
Mean (x̄) = (Σxᵢ) / n
Variance (σ²) = (Σxᵢ² / n) - (x̄)²
(x + y)² = x² + y² + 2xy
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📋 Question Details
- Chapter
- Statistics
- Topic
- Mean and Variance
- Year
- 2020
- Shift
- 07 Jan Shift 2
- Q Number
- Q71
- Type
- Numerical
- NCERT Ref
- Class 11 Mathematics Ch 15: Statistics
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