- Tardigrade
- Question
- Mathematics
- Let the mean and standard deviation of marks of class A of 100 students be respectively 40 and α (> 0 ), and the mean and standard deviation of marks of class B of n students be respectively 55 and 30 -α. If the mean and variance of the marks of the combined class of 100+ n students are respectively 50 and 350 , then the sum of variances of classes A and B is :
Q. Let the mean and standard deviation of marks of class A of students be respectively and , and the mean and standard deviation of marks of class B of students be respectively and 30 . If the mean and variance of the marks of the combined class of students are respectively and , then the sum of variances of classes and is :
Solution: