A class teacher has the following absentee record of 40 students of a class for the whole term. Find the mean number of days a student was absent.

Find the mean weight of 20 students in your class.

If 30 of the 36 students of a class were present on a certain day,what percentage of students were absent?

Following is the data showing weights of 40 students in a class . Find its median .

The students in three classes are in the ratio of 2:3:4. If 40 students are added in each clas, the ratio becomes 4:5:6. Find the total number of students in all the three classes is :

To maintain interest among students in class, a teacher should:

A school keeps medical record of all the students.Following table shows the gain in weights by 40 students of Class X in a year. Find the median gain in weight.

In Class XI of a certain school, there are 30 students in a Mathematics class and 20 students in Biolog class. Find the number of students which are in Mathematics class or in Biology class in the following cases: (i) Two classes are conducted at the same time. (ii) Two classes are condcuted at different time and 5 students study both the subject