0-10 , 10 - 20 , 20 - 30 , ...., are the classes , the lower boundary of the class 20-30 is `"_______"`.

The width of the class interval 20- 30 is

Find the class mark of the class 10 -20.

If 1-5 , 6 -10 , 11-15 , 16-20, ..., are the classes of a frequency distribution , then the lower boundary of the class 11-15 is "_______" .

If 1-10, 11-20, 21-30, 31-40, ......., are the classes of a frequency distribution, then the upper boundary of the class 31-40 is _____.

In the class interval 20 - 30, the lower class limit is _______

Write the upper class limit and the lower class limit of the class 20 - 30.

Mid value of the class 10 - 20 is ......

0- 10, 11- 20, 21 - 30, 31 -40. The real lower limit of the class 21 - 30 is

For overlaping classes 0-10,10-20,20-30, etc.Then the class mark of the class 0-10 is

The classes are 5 -9 , 10-14,15-19,20-24,... Find the lower boundary of the class 10-14.