Q68.The mean and variance of a set of 15 numbers are 12 and 14 respectively. The mean and variance of another set of 15 numbers are 14 and ๐2 respectively. If the variance of all the 30 numbers in the two sets is 13, then ๐2 is equal to (1) 10 (2) 11 (3) 9 (4) 12
What This Question Tests
The question requires applying the formula for combined variance of two sets of data, given their individual means and variances, to find an unknown variance.
Concepts Tested
Formulas Used
Variance (ฯยฒ) = (ฮฃxยฒ/N) - (mean)ยฒ
Formula for combined variance of two groups
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๐ Question Details
- Chapter
- Statistics
- Topic
- Combined variance of two sets of data
- Year
- 2023
- Shift
- 06 Apr Shift 1
- Q Number
- Q68
- Type
- MCQ
- NCERT Ref
- Class 11 Mathematics Ch 15: Statistics
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