Question

Consider a poison distribution with a mean ¡=3 then P( X<2) is
1. 0.2240
2. 0.1992
3. 0.4232
4. 0.1494
5. 0.4223

Answer 1

$P( X<2)=P( X=0)+P( X=1)\\ =\frac{e^{-3}3^{0}}{0!}+\frac{e^{-3}3^{1}}{1!}\\ \approx 0.1992$