There are 20 values. The square root of 20 is 4.47 so rounding up gives 5 bins.
The tables compare two alternatives, 8 ranges with a span of five and 5 ranges of span ten (I haven't counted the first and last bins because they are empty:
|
|
Range
|
Bin
|
Frequency
|
|
35-40
|
40
|
0
|
|
>40-45
|
45
|
2
|
|
>45-50
|
50
|
2
|
|
>50-55
|
55
|
3
|
|
>55-60
|
60
|
3
|
|
>60-65
|
65
|
4
|
|
>65-70
|
70
|
2
|
|
>70-75
|
75
|
0
|
|
>75-80
|
80
|
3
|
|
>80-85
|
85
|
1
|
|
|
Range
|
Bin
|
Frequency
|
|
25-35
|
35
|
0
|
|
>35-45
|
45
|
2
|
|
>45-55
|
55
|
5
|
|
>55-65
|
65
|
7
|
|
>65-75
|
75
|
2
|
|
>75-85
|
85
|
4
|
|
>85-95
|
95
|
0
|
|
spreadsheet
 |
Move your mouse over the histogram to see the alternative:
|
|
 |
Which histogram do you think is preferable, and why?
|