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Question: The A.M. of n observations is M. If the sum of \(n - 4\) observations is a, then the mean of remaini...

The A.M. of n observations is M. If the sum of n−4n - 4 observations is a, then the mean of remaining 4 observations is

A

nM−a4\frac{nM - a}{4}

B

nM+a2\frac{nM + a}{2}

C

nM−A2\frac{nM - A}{2}

D

n M + a

Answer

nM−a4\frac{nM - a}{4}

Explanation

Solution

Let the mean of the remaining 4 observations be xˉ1{\bar{x}}_{1}.

Then, M=a+4xˉ1(n−4)+4M = \frac{a + 4{\bar{x}}_{1}}{(n - 4) + 4}⇒ x1‾=nM−a4\overline{x_{1}} = \frac{nM - a}{4}.