A random variable $X$ has the following distribution \begin{array}{lllllllll} \hline \begin{array}{l} Values…

A random variable $X$ has the following distribution \begin{array}{lllllllll} \hline \begin{array}{l} Values of \\ X(x) \end{array} & 0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 \\ \hlineP(X=x) \quad 0 & k & 2 k & 2 k & 3 k & k^2 & 2 k^2 & 7 k^2+k \\ \hline \end{array}
  1. $\frac{9}{10}$
  2. $\left(\frac{9}{10}\right)^2$
  3. $\left(\frac{3}{10}\right)$
  4. $\frac{1}{10}$

Solution

$ \begin{aligned} & \text { Since, } \Sigma P\left(X=x_i\right)=1 \\ & \Rightarrow 0+K+2 K+2 K+3 K+K^2+2 K^2 \\ & +7 K^2+K=1 \\ & \Rightarrow \quad 9 K+10 K^2=1 \\ & \Rightarrow \quad K=\frac{1}{10}, \quad[\because K>0] \\ & \end{aligned} $ So, $ \begin{aligned} & P(0 < K < 6)=K+2 K+2 K+3 K+K^2 \\ & =8 K+K^2=\frac{8}{10}+\frac{1}{100}=\frac{81}{100}=\left(\frac{9}{10}\right)^2 \end{aligned} $

Asked in: AP EAMCET 2018 (23 Apr Shift 2)

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