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Let \mathrm{ X}  be a binomially distributed random variable with mean 4 and variance \mathrm{ \frac{4}{3}}. Then,\mathrm{ 54 \, \, P(X \leq 2)} is equal to

Option: 1

\frac{73}{27}


Option: 2

\frac{146}{27}


Option: 3

\frac{146}{81}


Option: 4

\frac{126}{81}


Answers (1)

best_answer

\mathrm{n p =4} \\

\mathrm{n p q =\frac{4}{3} }\\

\mathrm{\Rightarrow q =\frac{1}{3} \Rightarrow 1-p=\frac{1}{3} \Rightarrow p=\frac{2}{3}} \\

\mathrm{\Rightarrow n =6}

\mathrm{\therefore\; 54 P(x \leq 2)} \\

\mathrm{=54[P(0)+P(1)+P(2)]} \\

\mathrm{=54\left[{ }^{6} C_{0} \cdot\left(\frac{1}{3}\right)^{6}+{ }^{6} C_{1}\left(\frac{2}{3}\right)^{5}\left(\frac{1}{3}\right)\right. \left.+{ }^{6} C_{2}\left(\frac{2}{3}\right)^{4}\left(\frac{1}{3}\right)^{2}\right] }

=54\left[\frac{1}{3^{6}}(1+6 \cdot 32+15 \cdot 16)\right] \\

=\frac{146}{27}

Hence correct option is 2

Posted by

vishal kumar

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