Let the mean and standard deviation of marks of class A of 100 students be respectively 40 and α 0, and the…

Question

Let the **mean** and **standard deviation** of marks of class **A** of **$$100$$** students be respectively **$$40$$** and $$\alpha > 0$$, and the mean and standard deviation of marks of class **B** of $$n$$ students be respectively **$$55$$** and $$30-\alpha$$. 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:

Accepted Answer

A. $$500$$

Answer

B. $$650$$

Answer

C. $$450$$

Answer

D. $$900$$

Answer & step-by-step solution

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