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If the values $1, \frac{1}{2}, \frac{1}{3}, \frac{1}{4}, \frac{1}{5}, \ldots \ldots, \frac{1}{n}$ occur at frequencies 1 , $2,3,4,5, \ldots, n$ in a distribution, then the mean is
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The correct answer is:
$\frac{2}{n+1}$
Mean $=\frac{1 \cdot 1+\frac{1}{2} \cdot 2+\frac{1}{3} \cdot 3+\frac{1}{4} \cdot 4+\frac{1}{5} \cdot 5+\ldots . .+\frac{1}{n} n}{1+2+3+\ldots . .+n}$
$=\frac{1+1+1+1+\ldots .+1}{\frac{n(n+1)}{2}}=\frac{n}{\frac{n(n+1)}{2}}=\frac{2}{n+1}$.
$=\frac{1+1+1+1+\ldots .+1}{\frac{n(n+1)}{2}}=\frac{n}{\frac{n(n+1)}{2}}=\frac{2}{n+1}$.
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