The class interval is a range of values used to group data in a histogram, with class boundaries separating each interval. The class size is the width of each interval, and the class mark is the midpoint of each interval.
The class interval is a range of values that is used to group data in a histogram.
For example, in the given histogram, the class intervals are 50 to less than 60, 60 to less than 70, 70 to less than 80, 80 to less than 90, and 90 to less than 100.
The class boundaries are the values that separate one class interval from another. In this case, the class boundaries are 50 and 60, 60 and 70, 70 and 80, 80 and 90, and 90 and 100.
The class size is the width of each class interval. In this example, the class size is 10 because each class interval has a width of 10.
The class mark is the midpoint of each class interval.
To find the class mark, you can add the lower and upper boundary of each class interval and divide by 2.
For instance, the class mark for the first interval would be (50 + 60) / 2 = 55.