# T.R. Jain and V.K. Ohri Solutions Class 11 Statistics Economics Chapter 11 - Measures of Dispersion

T.R. Jain and V.K. Ohri Solutions for Class 11 Statistics for Economics Chapter 11 – Measures of Dispersion is regarded as an important concept to be studied thoroughly by the students. Here, we have provided T.R. Jain and V.K. Ohri Solutions for Class 11.

 Board CBSE Class Class 11 Subject Statistics for economics Chapter Chapter 11 Chapter Name Measures of dispersion Number of questions solved 03 Category T.R. Jain and V.K. Ohri

Chapter 11 – Measures of Dispersion covers the following concepts:

• Concept and measures of dispersion
• Methods of measuring dispersion
• Mean deviation
• Standard deviation

## T.R. Jain and V.K. Ohri Solutions for Class 11 Statistics for Economics Chapter 11 – Measures of Dispersion

### Question 1

Find the interquartile range, quartile deviation and coefficient of quartile deviation from the following data:

 Marks 28 18 20 24 27 30 15

Solution:

Firstly, arrange the data in the ascending order:

 S.No. Marks 1 15 2 18 3 20 4 24 5 27 6 28 7 30 N = 7

Q1 =

$$\begin{array}{l}Size \, of\left (\frac{N+1}{4}\right)th \, item\, = Size \, of\, \left (\frac{7+1}{4}\right)th\, item\end{array}$$

= Size of 2nd item = 18 marks

Q3 =

$$\begin{array}{l}Size\, of\,3\left(\frac{N+1}{4}\right)th\, item = Size\, of\,3\left(\frac{7+1}{4}\right)th\, item\end{array}$$

= Size of 6th item = 28 marks

Interquartile range = Q3 – Q1 = 28-18 = 10

$$\begin{array}{l}Quartile\, Deviation=\frac{Q3-Q1}{2}=\frac{28-18}{2}=5\end{array}$$
$$\begin{array}{l}Coefficient \, of \, Quartile \, Deviation = \frac{Q3-Q1}{Q3+Q1}=\frac{28-18}{28+18}=\frac{10}{46}=0.217\end{array}$$

### Question 2

What are the methods of Standard Deviation?

Solution:

The two standard methods of deviation are:

• Direct method
• Short-cut method

### Question 3

Define Dispersion.

Solution:

Dispersion is the measure of the extent to which the different items tend to disperse away from the central tendency.

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