$I.\,\,C{H_2} = CH - C{H_3} + \,{H_2}O\,\xrightarrow{{{H^ + }}}$
$II. \,\,C{H_3} - CHO\,\xrightarrow[{(ii)\,{H_2}O}]{{(i)\,C{H_3}MgI}}$
$III. \,\, C{H_2}O\,\xrightarrow[{(ii)\,{H_2}O}]{{(i)\,{C_2}{H_5}MgI}}$
$IV.\,\,C{H_2} = CH - C{H_3}\,\xrightarrow{{KMn{O_4}}}$
$\begin{array}{*{20}{c}}
{OH\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{C{H_3}CHC{H_2}C{H_2}N{H_2}}
\end{array}$ $\xrightarrow[{triethyla\min e}]{{ethyl\,formate\,\left( {1\,equiv} \right)}}$