Statistics — Class 11 Mathematics

Core Concepts

Dispersion measures how far observations spread around a central value. Range is maximum−minimum. Variance is the mean of squared deviations from the mean, and standard deviation is the positive square root of variance.

Worked Example

For data 2,4,6,8,10, mean=6. Deviations are −4,−2,0,2,4; squared deviations total 40. Population variance=40/5=8 and standard deviation=√8.

Explained MCQs

1. Range of 3,7,11,15 is 12.
2. Standard deviation is the square root of variance.
3. A smaller standard deviation generally indicates less spread around the mean.

Practice

1. Find the range of 12,5,18,9,21.
2. Calculate variance and standard deviation for 1,2,3,4,5.