Prepare the class limits and class boundaries . The lowest is 54 and largest value is 105. The data will be divided into seven classes.
Class limits are the smallest and largest observations (data, events etc) in each class. Therefore, each class has two limits: a lower and upper.
Here, the largest value=105 and the lowest value=54. The data will be divided into seven classes.
Therefore, class interval =(largest value - lowest value)/No. of classes you want to have
Class interval should always be a whole number and yet in this case we have a decimal number. The solution to this problem is to round off to the nearest whole number. So, 7.285 gets rounded up to 7.
54 and (54+7)=61 would be the class limits(lower=54, upper=61) of the first class. Similarly, we can compute the other class limits.
Therefore, 54-61, 62-69, 70-77, 78-85, 86-93, 94-101 and 102-109 would be the class limits.
Class Boundaries are the midpoints between the upper class limit of a class and the lower class limit of the next class in the sequence. Therefore, each class has an upper and lower class boundary.
For the first class, 54 – 61
The lower class boundary is the midpoint between 53 and 54, that is 53.5. The upper class boundary is the midpoint between 61 and 62, that is 62.5.
Similarly, we can compute the lower and the upper class boundaries for other classes.
Therefore, the class boundaries are 53.5-62.5, 62.5-69.5, 69.5-77.5, 77.5-85.5, 85.5-93.5, 93.5-101.5 and 101.5-109.5.