13.Statistics
hard

ધારોકે નીચેના વિતરણ નું મધ્યક $\mu$ અને પ્રમાણિત વિચલન $\sigma$ છે. 

$X_i$ $0$ $1$ $2$ $3$ $4$ $5$
$f_i$ $k+2$ $2k$ $K^{2}-1$ $K^{2}-1$ $K^{2}-1$ $k-3$

 જ્યાં $\sum f_i=62$. જો $[x]$ એ મહત્તમ પૂર્ણાક $\leq x$ દર્શાવે,તો $\left[\mu^2+\sigma^2\right]=.......$

A

$8$

B

$7$

C

$6$

D

$9$

(JEE MAIN-2023)

Solution

$\sum f _{ i }=62$

$3 k ^2+16 k -12 k -64=0$

$k =\text { or }-\frac{16}{3}(\text { rejected) }$

$\mu=\frac{\sum f _{ i } x _{ i }}{\sum f _{ i }}$

$\mu=\frac{8+2(15)+3(15)+4(17)+5}{62}=\frac{156}{62}$

$\sigma^2=\sum f _{ i } x _{ i }^2-\left(\sum f _{ i } x _{ i }\right)^2$

$=\frac{8 \times 1^2+15 \times 13+17 \times 16+25}{62}-\left(\frac{156}{62}\right)^2$

$\sigma^2=\frac{500}{62}-\left(\frac{156}{62}\right)^2$

$\sigma^2+\mu^2=\frac{500}{62}$

${\left[\sigma^2+\mu^2\right]=8}$

Standard 11
Mathematics

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