Given $E[Y]=1$ , $E[Y^2]=2$ and $E[Y^3]=5$, Y non negative integer random variable, find min of $P[Y=0]$

If $Y$ is a non negative integer-valued random variable with $E[Y]=1$, $E[Y^2]=2$ and $E[Y^3]=5$ ,where $E$ is the average value of $Y$. Find the minimum value of the possibility $P[Y=0]$.

I know that $E[Y]=\sum^{n}_{i=1}y_{i}p(y_{i})$ and $E[Y]=\sum_{y:p(y)>0}yp(y)$.

I know that Markov's inequality is : $P[Y\geq a] \leq\frac{E[Y]}{a}$

I know that Chebyshev's inequality is : $P(|Y-E[Y]|\geq k)\leq \frac{Var(Y)}{k^2}$

The book I'm studying is the : A first course in probability 8th edition , Sheldon Ross


Let $f(Y) = (Y-1)(Y-2)(Y-3)$. Expectation $\mathbb E$ is linear so $$ \begin{eqnarray} \mathbb E(f(Y)) &=& \mathbb E((Y-1)(Y-2)(Y-3)) \\ &=&\mathbb E(Y^3-6 Y^2 + 11 Y -6) \\ &=& 5 - 6 \cdot 2 + 11 - 6 \\ &=& -2 \end{eqnarray}$$ Denote $p_k= \mathbb P(Y=k)$. Then another expression for the expectation is $$ \begin{eqnarray} \mathbb E(f(Y)) &=& p_0 f(0) + p_1 f(1) + p_2 f(2) + p_3 f(3) + \ldots \\ &=& -6 p_0 + 0 + 0 + 0 + \textrm{ non-negative terms} \\ &\geq& -6 p_0 \end{eqnarray}$$ So $-2 = \mathbb E(f(Y)) \geq -6 p_0$, or $p_0 \geq \tfrac13$.

This bound is sharp since we can take $p_0=\tfrac13$, $p_1=\tfrac12$, $p_3=\tfrac16$, and all other probabilities zero to get the required expectations for $Y$, $Y^2$, and $Y^3$.