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    Question

    If the average of s number is r⁴ and the average r

    number is s⁴, then find the average of all r+ s numbers
    A r s (r² +s² -r s) Correct Answer Incorrect Answer
    B r² + s² Correct Answer Incorrect Answer
    C r s (r² + s²) Correct Answer Incorrect Answer
    D r s (r² +s² -r s) Correct Answer Incorrect Answer

    Solution

    The average of the s number is = r⁴ total sum of s number = r⁴ × s  and the average of r number = s⁴ total of r number = s⁴ × r  so now the average of r +s number = (r⁴ × s + s⁴ × r )/ r + s  = r s (r³ +s³)/r +s =r s (r+ s) (r² +s² -r s)/r + s =r s (r² +s² -r s)

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