The class mark of the class 90-130 is:

The range of the data:
25, 81, 20, 22, 16, 6, 17,15,12, 30, 32, 10, 91, 8, 11, 20 is

In a frequency distribution, the mid value of a class is 10 and the width of the class is 6. The upper limit of the class is:

The width of each of five continuous classes in a frequency distribution is 5 and the lower class-limit of the lowest class is 10. The lower class-limit of the highest class is:

Let m be the mid-point and 1 be the lower class limit of a class in a continuous frequency distribution. The upper class limit of the class is:

The class marks of a frequency distribution are given as follows:
15, 20, 25, ...
The class corresponding to the class mark 15 is:

In the class intervals 10-20, 20-30, the number 20 is included in:

A grouped frequency table with class intervals of equal sizes using 250-270 (270 not included in this interval) as one of the class interval is constructed for the following data:
268, 220, 368, 258, 242, 310, 272, 342, 310, 290, 300, 320, 319, 304,402, 318, 406, 292, 354, 278, 210, 240, 330, 316, 406, 215, 258, 236. The frequency of the class 370-390 is:

A grouped frequency distribution table with classes of equal sizes using 63-72 (72 included) as one of the class is constructed for the following data:
30, 32, 45, 54, 74, 78, 108, 112, 66, 76, 88, 40, 14, 20, 15, 35, 44, 66, 75, 84, 95, 96, 102, 110, 88, 74, 112, 14, 34, 44. The number of classes in the distribution will be:

To draw a histogram to represent the following frequency distribution:

the adjusted frequency for the class 25-45 is: