S.D. of 5 scores 1, 2, 3, 4, 5 is

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13.Statistics

medium

The $S.D.$ of $5$ scores $1, 2, 3, 4, 5$ is

A

$\frac{2}{5}$

B

$\frac{3}{5}$

C

$\sqrt 2 $

D

$\sqrt 3 $

Solution

(c) Mean $\bar x = \frac{{1 + 2 + 3 + 4 + 5}}{5} = 3$

$S.D.$ = $\sigma $ = $\sqrt {\frac{1}{n}\sum {x_i^2 – (\bar x} {)^2}} $

=$\sqrt {\frac{1}{5}(1 + 4 + 9 + 16 + 25) – 9} $=$\sqrt {11 – 9} = \sqrt 2 $.

Standard 11

Mathematics

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