The length of 40 leaves of a plant are measured correct to one millimetre, and the obtained data is represented in the following table: (i) Draw a histogram to represent the given data. [Hint: First make the class intervals continuous] (ii) Is there any other suitable graphical representation for the same data?

Length(in mm) New length(in mm) No. of leaves
118 - 126 117.5 - 126.5 3
127 - 135 126.5 - 135.5 5
136 - 144 135.5 - 144.5 9
145 - 153 144.5 - 153.5 12
154 - 162 153.5 - 162.5 5
163 - 171 162.5 - 171.5 4
172 - 180 171.5 - 180.5 2
In order to make a histogram, we need to convert discontinuous classes to continuous classes.
Adjustment = 1/2(lower limit of class - upper limit of previous class) = 1/2(127 - 126) = 0.5
So, 0.5 needs to be subtracted from the upper limit of the previous class and added to the lower limit of the next class.
(ii) Frequency polygon
(iii) No. It is a range. The maximum number of leaves lies between 144.5 mm and 153.5 mm. It is not necessary that they all occur at a length of 153 mm.