Final answer:
The class width of the given data set with a maximum value of 100 and a minimum value of 64, using 7 classes, is 5.
Step-by-step explanation:
To find the class width of a set of data, you need to determine the range of the data and divide it by the number of classes. In this case, the maximum value is 100 and the minimum value is 64. So, the range of the data is 100 - 64 = 36. Since you are using 7 classes, you will divide the range by 7 to find the class width. Therefore, the class width is 36 / 7 = 5.14 (rounded to the nearest whole number).