If we draw a histogram for the class interval 15 - 30, what will be the value of 'a' ?
Comparing the table and the graph we can pbserve
d = 30
When a frequency distribution table is depicted using histograms,
the number of tally marks of a class interval is represented using the height of bars in the histogram.
Here, when the class interval 15 - 30 is depicted in a histogram since the tally marks are 7,
the value of a = 7,
as the height of the bar is 7.