If the mean of m observations out of n observations is n and the mean of remaini

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Question
If the mean of m observations out of n observations is n and the mean of remaining observations is m, then what is the mean of all n observations?
Options
A. 2m ?m^2/n
B. 2m ?m/n
C. 2m
D. 2m ?m

Correct Answer

2m ?m^2/n

Explanation

Mean of m observations is n

Mean of n-m observations is m

So total = nm+ (n-m)m

Total observations = n

Mean = Total / Total observations = (2mn-m^2)/n = 2m ?m^2/n

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Options
A. Rs. 1600
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A man invested Rs. 4455 in Rs. 10 shares quoted at Rs. 8.25. If the rate of dividend be 6% his annual income is?
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