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13.Statistics
hard

નીચે આપેલ માહિતીનું વિચરણ શોધો.

વસ્તુ નું કદ 

$3.5$

$4.5$

$5.5$

$6.5$

$7.5$

$8.5$

$9.5$

આવ્રુતિ 

 $3$

$ 7$

$22$

$60$

$85$

$32$

$8$

A

$1.29$

B

$2.19$

C

$1.32$

D

આપેલ પૈકી એક પણ નહિં

Solution

ધારેલો મધ્યક  $ a = 6.5   $ 

વિચરણની ગણતરી

$ xi$

         $f_i$

$d_i = x_i – 6.5$

     $f_id_i$

     $f_id_i^2$

$3.5$

         $3$

        $-3$

     $-9$

     $27$

$4.5$

      $   7$

       $ -2$

    $-14$

     $28$

$5.5$

       $22$

        $-1$

    $-22$

     $22$

$6.5$

      $  60$

     $   0$

     $0$

     $0$

$7.5$

       $ 85$

      $  1$

    $85$

     $85$

$8.5$

        $32$

        $2$

    $64$

    $128$

$9.5$

         $8$

        $3$

    $24$

     $72$

 

$N = Sf_i = 217$

 

$Sf_id_i = 128$

$Sf_id_i^2 = 362$

અહી $N\,\, = \,\,217,\,\,\,\,\,\,\Sigma \,{f_i}{d_i}\, = \,\,128$ અને $\Sigma {f_i}{d_i}^2\,\, = \,\,362$

$\therefore \,\,Var\,(X)\,\, = \,\,\left( {\frac{1}{N}\Sigma \,{f_i}d_i^2} \right)\,\, – \,\,{\left( {\frac{1}{N}\Sigma \,{f_i}{d_i}} \right)^2}\,\,\,\,\,$

$ = \,\,\frac{{362}}{{217}}\,\, – \,\,{\left( {\frac{{128}}{{217}}} \right)^2}\,\,\,\,\, = \,\,1.668\,\, – \,\,0.347\,\,\,\,\, = \,\,1.321$

 

Standard 11
Mathematics

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