Question

Here is a data set:

123	139	165	168
155	108	258	130
183	157	137	93
188	154	188	172
195	133	99	134
160	119	132	178
153	63	179	109

The goal is to construct a grouped frequency distribution table (GFDT) for this data set. The GFDT should have 10 classes with a "nice" class width. Each class should contain its lower class limit, and the lower class limits should all be multiples of the class width.

This problem is to determine what the class width and the first lower class limit should be.

What is the best class width for this data set?
optimal class width = Correct

What should be the first lower class limit?
1st lower class limit =

Answer 1

Given data in ascending

63
93
99
108
109
119
123
130
132
133
134
137
139
153
154
155
157
160
165
168
172
178
179
183
188
188
195
258

Minimum Value=63

Maximum=258

Range=258-63=195

Class width=(Range)/No.of Class=195/10=19.5

Take the class width=20

Frequency Distribution

Classes	Frequency
60-80	1
80-100	2
100-120	3
120-140	7
140-160	4
160-180	6
180-200	4
200-220	0
220-240	0
240-260	1
Total	28

What is the best class width for this data set?

Ans: 20

What should be the first lower class limit?

Ans: 60