Here is a quick way to review statistics. With this Quick Review, you can learn quickly Important Definitions, Important Facts, Important Formulae, and Important Procedures of chapter Statistics. If you have doubts, you can post it to our 24 x 7 x 365 discussion forum and let one of the experts help you. Watch statistics videos to see how to use these formulas to solve problems: https://www.youtube.com/watch?v=YXDqnJs5kGE&list=PLjBKjfW4DQUO3emCCdwsjh7ZG-mb36TMp

1. MB1014: Statistics
Quick Review
 1350+ Videos;
 Well-detailed solutions to 3500+ problems
 Practice assignments
Get FREE Help in Maths at www.mathbuster.in
 HOTS quizzes
 Self-assessment quizzes
 Model Test Papers
 Expert guidance by mathematicians
Buy Your Online Subscription Today (Starting at Rs. 199 per month) and Enjoy:
24 x 7 x 365 Access
to high quality content to learn, practice and assess.
24 x 7 x 365 Question & Answer Forum
to get the best help for your doubts and difficulties.
Learn math anywhere, anytime with
students from across India and abroad.
© 2013 – 2018, ECPL, New Delhi. This document is part of the MathBuster online education program. All intellectual rights associated to this document directly or indirectly are
owned by ECPL and any reproduction, derivation or distribution of this document in original or modified in full or parts, either in manual or electronic form is prohibited unless a
written approval is obtained. This document has been downloaded from www.mathbuster.in for personal and non-commercial use. For any queries, contact math@elipsis.in
1
Thank you!
We appreciate your visiting MathBuster and downloading this study document.
If you have any doubts or difficulties, send your queries to mathbusterforum@googlegroups.com
Important Definitions
1. The mean (or average) of observations is the sum of the values of all the observations divided by the total
number of observations.
2. Deviation is the difference between assumed mean ‘a’ and each of the individual observation ‘xi’.
3. Median is the value of middlemost observation in the data.
4. Mode is that value among the observations which occurs most often, that is, the value of the
observation having the maximum frequency.
5. The cumulative frequency of a class is the frequency obtained by adding the frequencies of all the
classes preceding the given class.
6. Modal Class is that Class Interval which contains Mode.
Important Facts
1. The median of raw data could be found by arranging the data either in ascending or descending order
and then by use of the appropriate formulae.
2. Ogive Curve is the graphic illustration of Cumulative Frequency on Y Axis with Class Interval on X
Axis.
3. There are two type of Ogives one less than Ogive and other greater than Ogive.
4. The median of grouped data can be obtained graphically as the x-coordinate of the point of
intersection of the two Ogives for this data.

2. MB1014: Statistics
Quick Review
 1350+ Videos;
 Well-detailed solutions to 3500+ problems
 Practice assignments
Get FREE Help in Maths at www.mathbuster.in
 HOTS quizzes
 Self-assessment quizzes
 Model Test Papers
 Expert guidance by mathematicians
Buy Your Online Subscription Today (Starting at Rs. 199 per month) and Enjoy:
24 x 7 x 365 Access
to high quality content to learn, practice and assess.
24 x 7 x 365 Question & Answer Forum
to get the best help for your doubts and difficulties.
Learn math anywhere, anytime with
students from across India and abroad.
© 2013 – 2018, ECPL, New Delhi. This document is part of the MathBuster online education program. All intellectual rights associated to this document directly or indirectly are
owned by ECPL and any reproduction, derivation or distribution of this document in original or modified in full or parts, either in manual or electronic form is prohibited unless a
written approval is obtained. This document has been downloaded from www.mathbuster.in for personal and non-commercial use. For any queries, contact math@elipsis.in
2
Important Formulae
1. The mean for grouped data can be found by:
a. Direct method:
.i i
i
f x
x
f



where, f = frequency and x = class mark.
b. Assumed mean method:
.i i
i
f d
x a
f
 


Where, f = frequency, a = assumed mean and d = deviation from assumed mean.
c. Step deviation method:
,i i
i
f u
x a h
f
 
    
 


where, f = frequency, a = assumed mean, h = Class Size, and
( )i
i
x a
u
h


With the assumption that the frequency of a class is centred at its mid point, called it’s
class mark.
2. The mode for grouped data can be found by:
1 0
1 0 2
Mode ,
2
f f
l h
f f f
 
   
  
where, l = lower limit of the modal class,
h = size of the class interval (assuming all class sizes to be equal),
f1 = frequency of the modal class,

3. MB1014: Statistics
Quick Review
 1350+ Videos;
 Well-detailed solutions to 3500+ problems
 Practice assignments
Get FREE Help in Maths at www.mathbuster.in
 HOTS quizzes
 Self-assessment quizzes
 Model Test Papers
 Expert guidance by mathematicians
Buy Your Online Subscription Today (Starting at Rs. 199 per month) and Enjoy:
24 x 7 x 365 Access
to high quality content to learn, practice and assess.
24 x 7 x 365 Question & Answer Forum
to get the best help for your doubts and difficulties.
Learn math anywhere, anytime with
students from across India and abroad.
© 2013 – 2018, ECPL, New Delhi. This document is part of the MathBuster online education program. All intellectual rights associated to this document directly or indirectly are
owned by ECPL and any reproduction, derivation or distribution of this document in original or modified in full or parts, either in manual or electronic form is prohibited unless a
written approval is obtained. This document has been downloaded from www.mathbuster.in for personal and non-commercial use. For any queries, contact math@elipsis.in
3
f0 = frequency of the class preceding the modal class,
f2 = frequency of the class succeeding the modal class.
3.
 Upper Limit+Lower Limit
ClassMark
2

4. Median for ungrouped data is formed by using the formula:
Median= Value of
1
2
th
n  
 
 
term, if n is odd
1
2 2
Median
2
th th
n n
term term
    
           , if n is even
where n = number of observations
5. The median for grouped data is formed by using the formula:
cf
2Median ,
n
l h
f
 
 
   
 
 
where, l = lower limit of median class,
n = number of observations,
cf = cumulative frequency of class preceding the median class,
f = frequency of median class,
h = class size (assuming class size to be equal).
6. Relationship between three measures of Central Tendency i.e Mean, Mode & Median is given by :
3 Median = Mode + 2 Mean.