This document provides information about Statisticshelpdesk, a website that offers statistics homework help and assistance with statistics assignments, projects, and dissertations. It also provides sample statistics questions and explanations of key statistical concepts like class boundaries, class limits, and mid-values. Statisticshelpdesk aims to help students with all aspects of statistics by providing tutoring, software help, and statistical analysis support.

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Statistics Homework Help
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1/16/2015
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Copyright © 2012 Statisticshelpdesk.com, All rights reserved

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About Statistics:
Statisticshelpdesk provides solution to all kind of problems related to
statistics, as it is a dedicated site of statistics so it provides all sorts of
help i.e Assignment help, Homework help, Project help, Dissertation
help, Live online tutoring, Statistical analysis, All sorts of software help
that are being used in statistics.
Statistics homework help will be viewed in numerous ways that.
Normally it's thought-about to subsume graphs, charts, percentages,
and averages. It consists of rules and strategies of collecting and presenting numerical data. It
conjointly consists of constructing inferences from a given knowledge. The statistical data will be
used to elucidate unexplained things, to form and justify a claim, to form comparisons, to seek
out unknown quantities, to predict data regarding future and to ascertain relationship between
quantities. Thus, it's a subject matter that consists of quite numbers.
Statistics Sample Questions and Solutions
ILLUSTRATION 1.
From the following data determine by Sturge’s rule the number of classes to be formed and the
interval of each such classes :
Number of observation = 60
Value of largest observation = 95
Value of the smallest observation = 5
SOLUTION:
According to struges rule the number of classes to be formed is given by
K(s) =1+3.322log N
= 1+3.322 log 60
= 1+1.322(1.7782) = 1+5.9072.
Further, according to the said rule, the size of classes interval for each of the classes is given by
i(s) =
L−S
K(s)
95−5
7
=
90
7
= 13 approx
Thus, the number of classes to be formed is 7 and the classes interval of each such class should
be 13.

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(iv) Class boundary:- Class boundaries or class walls mean the two extreme values of a class
to which the data belonging to the said class cannot cross or exceeds either way. He lower of
the two is called the lower boundary and the higher of the two id called the upper boundary of
the class. In class of exclusive classification, all the values of the class remain below the upper
boundary but in case of inclusive classification, all the values of a class remain within the two
boundaries ending with the upper one .the following example will indicate the class boundaries
under each of the two types of classification.
Example: Class Boundaries
In case of exclusive classes In case of exclusive classes
Lower boundary Upper boundary Lower boundary Upper boundary
0-10
10-20
20-30
30-40
40-50
0-9
10-19
20-29
30-39
40-49

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(v) Class limits. Class limits mean the two extreme values of a class within which all the values
of the class remain. The lower value of the class is called the lower limit and the upper value
below which all the data remain is called the upper limit of the class. the lower limit is designed
by L1 while the upper limit by L2 in case of exclusive classification the class limit are equal to
the class boundaries explained above. But in case of inclusive classification, the class limits cross
the class boundaries in both the directions. in such a case, the lower limit of a class is
determined by subtracting from the lower boundary of the class half of the difference between
the last significant digit of the upper boundary of the class and the last significant digit of the
lower boundary of the next class. Similarly, the upper limit of the class is determined by adding.
to the upper boundary of the class , half the difference between the last integer of the upper
boundary of the class and last integer of the lower boundary of the next class.
Symbolically, the lower limit and the upper limit of the inclusive class can be computed as
under:
Where L1 = lower limit of a class , L2 = upper limit of a class , B1=lower boundary of a class ,
B2 = upper boundary of a class , and d = difference between the last significant digit of the
upper boundary of the class and the last significant digit of the lower boundary of the next class.
In the above manner, in inclusive series is converted into an exclusive one for determining the
values of certain measures viz, median, quartiles, percentiles, mode etc . That depend upon the
exact class limits of the respective classes.
The following examples will show the class limits of the different classes formed under both the
exclusive and inclusive methods:
Example1:
L1=B1-
1
2
𝑑
and
L2 = B2+-
1
2
𝑑
Exclusive Classes Inclusive Classes
Classes Class-Limits Classes Class-Limits
B1 B2 L1 L2 B1 B2 L1 L2
0-10
10-20
20-25.5
25.5-30.5
30.5-35.5
0
10
20
25.5
30.5
10
20
25.5
30.5
35.5
0-9
10-19
20-29
30-39
40-49
-.5
9.5
19.5
29.5
39.5
9.5
19.5
29.5
39.5
49.5

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Example 2:
Inclusive Series I Inclusive Classes II
Classes Class-Limits Classes Classes-Limits
B1 B2 L1 L2 B1 B2 L1 L2
10-19.9
20-29.9
30-39.9
40-49.9
50.59.9
9.95
19.95
29.95
39.95
49.95
19.95
29.95
39.95
49.95
59.95
10-14.95
15-19.95
20-24.95
25-29.95
30-34.95
9.975
14.975
19.975
24.975
29.975
14.975
19.975
24.975
29.975
34.975
(vi) Mid-Value or Class Mark: The value that lies at the center of a class is called the mid –
value , mid-point or class mark of the said class. It is computed
M =
L1+L2
2
=
B1+B2
2
Where M= mid-value,
L1 and L2=Lower and upper limits of the class respectively,
And B1 and B2=lower and upper boundary of the class respectively.
Thus the mid-value of the class (10-20) =
10+20
2
=15 and that of (10-19) =
10+19
2
=14.5