Question

if s.d =13.42 and mean = 42 the coefficient of standard deviation=​

Answer 1

Explanation:

In earlier classes, you have studied measures of central tendency such as mean, mode,

median of ungrouped and grouped data. In addition to these measures, we often need

to calculate a second type of measure called a measure of dispersion which meas-

ures the variation in the observations about the middle value– mean or median etc.

This chapter is concerned with some important measures of dispersion such as

mean deviation, variance, standard deviation etc., and finally analysis of frequency

distributions.

15.1.1 Measures of dispersion

(a) RangeThe measure of dispersion which is easiest to understand and easiest to

calculate is the range. Range is defined as:

Range = Largest observation – Smallest observation

(b) Mean Deviation

(i) Mean deviation for ungrouped data:

For n observation x1

, x2

, ..., xn

, the mean deviation about their mean x is

given by

M.D ( x ) =

| | i

x x

n

−

(1)

Mean deviation about their median M is given by

M.D (M) =

| M | i

x

n

−

(2)

(ii) Mean deviation for discrete frequency distribution

Let the given data consist of discrete observations x1

, x2

, ... , xn

occurring with

frequencies f

1

, f

2

, ... , f

n

, respectively. In this case