If P(X=x)=k(x+1)3^-x, x=0,1,2,3,, find P(X2).

Question

If $P(X=x)=k(x+1)3^{-x}$, $x=0,1,2,3,\dots$, find $P(X\ge2)$.

Accepted Answer

As in Q34, $k=\dfrac49$.

$$P(X\ge2) = 1-P(0)-P(1) = 1-\frac49\left(1+\frac23\right) = 1-\frac{20}{27}=\frac{7}{27}$$

Solutions · 1