Mean of the getting mathematics number of 70 students is 45. If SD is. 18, then find the co-efficient of variation

If the sum of the squares of the differences of the 10 values of a variable from its mean 50 be 250, find the coefficient of variation.

Fill in the blanks If the mean marks of mathematics of n, students is barx_1 and that of n_2 students is barx_2 , then the mean marks of total students is_____.

The marks obtained in mathematics by 30 students of Class X of a certain scholl are given in table the below. Find the mean of the marks obtained by the students.

Find the mean if the coefficient of variation is 5% and variance is 4.

The number of students in a class is 60 . The average of the ages of the boy-students is 14.5 years and the average of the ages of the girl-students is 16 years . If the collective average of the total students be 15 years , then find the number of boy-students and the number of girl-students.

For a set of 20 observations A.M. is 4.0 and the coefficient of variation is 80 percent. Find the S.D.

Find the number of students to be selected at a time from a group of 14 students so that the number of sections is greatest. find the greatest number of selection. Also find the greatest number of selections when there are 15 students.

Find the number of students to be selected at a time from a group of 14 students so that the number of selections is greatest. Find the greatest number of selections. Also find the greatest number of selections when there are 15 students.

At present the sum of the number of students in all the secondary institutions in a district is 3993. If the number of students increased in a year was 10% of that in the previous year, then find the sum of the number of students in all the secondary institutions in the districts 3 years before?

The mean and SD of the scoreing marks of 100 students are 40 and 5.1 resp. on checking it was discovered that the score which should correctly read as 40 had been wrongly taken as 50. Find the correct values of mean and SD