Tag: measures of dispersion and skewness

Questions Related to measures of dispersion and skewness

if $25%$ of the items are less then $10% and 25%$are more than $40$ then the coefficient of quartile deviation is 

  1. $30$

  2. $50$

  3. $1.2$

  4. $0.6$


Correct Option: A

The suitable measure of central tendency for qualitative data is ______.

  1. mode

  2. arithmetic mean

  3. geometric mean

  4. median


Correct Option: D

Mean of a set of values is based on _______.

  1. all values

  2. $50$ percent values

  3. first and last value

  4. maximum & minimum value


Correct Option: A

For the following data:

Weekly Income (in Rs.): 58 59 60 61 62 63 64 65 66
No. of Workers: 2 3 6 15 10 5 4 3 1


The value of $\displaystyle\frac{Q _1+Q _3}{2}$ is equal to

  1. $Q _1$

  2. $Q _2$

  3. $Q _3$

  4. None of these


Correct Option: D
Explanation:

The cumulative frequency of the table is a given below:

Weekly income ( in Rs.) No. of workers Cumulative frequency
58 2 2
59 3 5
60 6 11
61 15 26
62 10 36
63 5 41
64 4 45
65 3 48
66 1 49
N = 49


Lower Quartile: 
We have $\displaystyle\frac{N}{4} = \displaystyle\frac{49}{4} = 12.25$
The cumulative frequency just greater than $\displaystyle\frac{N}{4}$ is $26$ and the corresponding value of the variable is $61$
$\therefore\quad Q _1 = Rs.\space 61$

Middle Quartile (median): 
We have $\displaystyle\frac{N}{2} = \displaystyle\frac{49}{2} = 24.5$
The cumulative frequency just greater than $\displaystyle\frac{N}{2}$ is $26$ and the corresponding value of the variable is $61$
$\therefore\quad Q _2 = Rs.\space 61$

Upper Quartile:
We have $\displaystyle\frac{3N}{4} = \displaystyle\frac{3\times49}{4} = 36.75$
The cumulative frequency just greater than $\displaystyle\frac{3N}{4}$ is $41$ and the corresponding value of the variable is $63$
$\therefore\quad Q _3 = Rs.\space 63$

$\therefore\quad \displaystyle\frac{Q _1+Q _3}{2} = \displaystyle\frac{61+63}{2} = 62$