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Measures Of Dispersion
Some measures of dispersion depend upon the spread of values whereas some calculate the variation of values from a central value. Do you agree?
Yes we agree with the statement Range and quartile deviation measure the dispersion by calculating the spread within which the values lie i.e. they depend on the spread of values. On the other hand, mean deviation and standard deviation calculate the variation of value from a central value.
Some More Questions From Measures of Dispersion Chapter
A batsman is to be selected for a cricket team. The choice is between X and Y on the basis of their five previous scores which are:
X
Y
25
50
85
70
40
65
80
45
120
80
Which batsman should be selected if we want
(i) a higher run getter, or
(ii) a more reliable batsman in the team?
X
Y
25
50
85
70
40
65
80
45
120
80
To check the quality of two brands of lightbulbs, their life in burning hours was estimated as under for 100 bulbs of each brand.
Life (in hrs)
No. of bulbs
Brand A
Brand B
0–50
15
2
50–100
20
8
100–150
18
60
150–200
25
25
200–250
22
5
100
100
(i) Which brand gives higher life?
(ii) Which brand is more dependable?
Life (in hrs)
No. of bulbs
Brand A
Brand B
0–50
15
2
50–100
20
8
100–150
18
60
150–200
25
25
200–250
22
5
100
100
Average daily wage of 50 workers of a factory was Rs. 200 with a standard deviation of Rs. 40. Each worker is given a raise of Rs. 20. What is the new average daily wage and standard deviation? Have the wages become more or less uniform?
In the previous question, calculate the relative measures of variation and indicate the value, which in your opinion is more reliable.
If in the previous question, each worker is given a hike of 10% in wages, how are the mean and standard deviation values affected?
The sum of 10 values is 100 and the sum of their squares is 1090. Find the coefficient of variation.
Calculate the mean deviation about mean and standard deviation for the following distribution:
Classes
Frequencies
20–40
3
40–80
6
80–100
20
100–120
12
120–140
9
50
Classes
Frequencies
20–40
3
40–80
6
80–100
20
100–120
12
120–140
9
50
A measure of dispersion is a good .supplement to the central value in understanding a frequency distribution. Comment
Define dispersion.
How many methods are there to calculate dipersion?
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Mock Test Series
Mock Test Series