Length (in mm) New length(in mm)No. of leaves  118 - 126117.5 - 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 $$= \\dfrac 12 (\\mbox {lower limit of class - upper limit of previous class)}$$=21​(127−126)=0.5So, 0.5 needs to be subtracted from upper limit of previous class and lower limit of next class.(ii) Frequency polygon(iii) No. It is a range. The maximum number of leaves lies in between 144.5mm−154.5mm. Not necessary that it all occurs as 153mm length.