Class 11 Maths Revision Notes for Statistics of Chapter 15


Class 11 Maths Revision Notes for Statistics of Chapter 15 – Free PDF Download

Free PDF download of Class 11 Maths revision notes & short key-notes for Statistics of Chapter 15 to score high marks in exams, prepared by expert mathematics teachers from latest edition of CBSE books.

Chapter NameStatistics
ChapterChapter 15
ClassClass 11
SubjectMaths Revision Notes
BoardCBSE
TEXTBOOKMatheMatics
CategoryREVISION NOTES

CBSE Class 11 Maths Revision Notes for Statistics of Chapter 15


Measure of Dispersion
The dispersion is the measure of variations in the values of the variable. It measures the degree of scatteredness of the observation in a distribution around the central value.
Range
The measure of dispersion which is easiest to understand and easiest to calculate is the range.
Range is defined as the difference between two extreme observation of the distribution.
Range of distribution = Largest observation – Smallest observation.
Mean Deviation
Mean deviation for ungrouped data
For n observations x1, x2, x3,…, xn, the mean deviation about their mean ar { x } is given by
Statistics Class 11 Notes Maths Chapter 15 1
Mean deviation about their median M is given by
Statistics Class 11 Notes Maths Chapter 15 2
Mean deviation for discrete frequency distribution
Let the given data consist of discrete observations x1, x2, x3,……., xn occurring with frequencies f1, f2, f3,……., fn respectively in case
Statistics Class 11 Notes Maths Chapter 15 3
Mean deviation about their Median M is given by
Statistics Class 11 Notes Maths Chapter 15 4
Mean deviation for continuous frequency distribution
Statistics Class 11 Notes Maths Chapter 15 5
where xi are the mid-points of the classes, ar { x } and M are respectively, the mean and median of the distribution.
Variance
Variance is the arithmetic mean of the square of the deviation about mean ar { x }.
Let x1, x2, ……xn be n observations with ar { x } as the mean, then the variance denoted by σ2, is given by
Statistics Class 11 Notes Maths Chapter 15 6
Standard deviation
If σ2 is the variance, then σ is called the standard deviation is given by
Statistics Class 11 Notes Maths Chapter 15 7
Standard deviation of a discrete frequency distribution is given by
Statistics Class 11 Notes Maths Chapter 15 8
Standard deviation of a continuous frequency distribution is given by
Statistics Class 11 Notes Maths Chapter 15 9
Coefficient of Variation
In order to compare two or more frequency distributions, we compare their coefficient of variations. The coefficient of variation is defined as
Statistics Class 11 Notes Maths Chapter 15 10
Note: The distribution having a greater coefficient of variation has more variability around the central value, then the distribution having a smaller value of the coefficient 0f variation.