Question

What type of data is best displayed with a histogram?

Answer 1

Histograms are normally used for grouped data.

class boundaries are the exact values(for each set of grouped data) where one set of values ends and the other begins.

In our example, the class boundaries are:
height(cm): 71-75,76-80,81-85,86-90, and 91-95
frequency:5,17,21,15,2

You must appreciate that these numbers are the 'deciders' as to which group data is placed.

For example 75.45 would be rounded down to 75 and be placed in the first group, but 75.55 would be rounded up an placed in the second.

class width is the width of each block of values(not frequencies).
In our example(above) height 71-75 gives a class width of 5 and NOT 4 (75-71). There are 5 numbers in the group 71 72 73 74 75.

grouping using inequalities The values are grouped according to an inequality rule.