\noindent{\bf Ans}:

\begin{eqnarray*}
&& f(p_1)f(p_0)<0 \Rightarrow a = p_0,\;b = p_1\\
&& f(p_2)f(p_0)<0 \Rightarrow a = p_0,\;b = p_2\\
&& f(p_3)f(p_0)<0 \Rightarrow a = p_0,\;b = p_3\\
&& f(p_4)f(p_0)<0 \Rightarrow a = p_0,\;b = p_4
\end{eqnarray*}
{\bf(up to here = 4 pts)}
$$
\Rightarrow p_5 = p_4 - f(p_4)\frac{p_4-p_0}{f(p_4)-f(p_0)}\;\textrm{{\bf(4 pts)}} = 0.6\;\textrm{{\bf(2 pts)}}.
$$