[size=150]The number of data points is relatively small, at 30. [br]The dot diagram can be used, but if we are to draw the dots individually, it would be tedious.[br]Likewise the stem and leaf diagram would be tedious if the values are to be written manually or typed.[br]However using appropriate software, the 3 diagrams can be relatively easy to draw.[br]As for visual representation, all three diagrams are easy to read.[br][br]The stem and leaf diagram allows you to easily get the individual values of the original data.[br]The dot diagram for this set of whole number values can also be seen from the x axis and the frequency of each value is taken from the dots above any given x value.[br][br]A histogram (for grouped data) however, does not show individual values, only the frequency of the values within each class interval. For example in the above, 13 students have test scores of between 0 to 10, inclusive of 10. But the exact scores of the 13 students cannot be found in the histogram.[br]It can only be found in the stem and leaf diagram or the dot diagram.[/size]

[size=150]When the class interval size is 5 units, there would be 6 rectangular bars whose heights would be shorter.[br]The frequencies within each of the 6 class interval has to be spread out from the original 3 intervals, so they are smaller. Hence the heights of the bars are shorter.[br][br][/size][size=150]As we increase the number of class intervals, ie. to smaller class widths, the heights of the bars will get shorter. It is also possible that within some interval, no values may be there, ie. frequency is zero in that class interval, hence there would be no bar in that interval. [br]Try number of intervals = 10 (class width of 3 units) to see this.[/size]