A random variable X has poisson distribution with mean 2. Then P(X>1.5) = 
 

Given X follows poisson distribution. 

Given that mean $\left(\mathrm{\lambda }\right)=2$

Now $(X>1.5)=\mathrm{P}(X\ge 2)$

                         $$\begin{gathered} =1-\mathrm{p}(X=0)-\mathrm{p}(X=1) \\ =1-{\mathrm{e}}^{-\mathrm{\lambda }}-\frac{{\mathrm{e}}^{-\mathrm{\lambda }}.{\mathrm{\lambda }}^1}{1!} \\ =1-{\mathrm{e}}^{-2}-2.{\mathrm{e}}^{-2} \\ =1-\frac{3}{{\mathrm{e}}^2} \end{gathered}$$