\documentclass[border=10pt]{standalone}
%% Source: https://tex.stackexchange.com/a/406814/95014%
%% Author: "cfr"%
%% Comment: Uses forest package for tikz%%
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{forest}
\usetikzlibrary{calc}

\tikzset{
  % Two node styles for game trees: solid and hollow
  solid node/.style={circle,draw,inner sep=1.5,fill=black},
  hollow node/.style={circle,draw,inner sep=1.5}
}
\begin{document}
\forestset{
  small_edge_label/.style 2 args={
    edge label={node[midway, font=\sffamily\scriptsize, #1]{#2}},
  },
  big_edge_label/.style 2 args={
    edge label={node[midway, font=\sffamily\normalsize, #1]{#2}},
  },
}

\begin{forest}
  for tree={
    parent anchor = east,
    child anchor = west,
    grow' = east,
    l sep'+=25pt,
    s sep'+=35pt,
    for children={
      l sep+=180pt,
      s sep+=30pt,
    }
  },
  [, hollow node, label=left:Chance
  [, hollow node, big_edge_label={left}{$Pr(yes)=0.1$}
  [, solid node, small_edge_label={above}{$Pr(pos|yes)=0.6$}, label=right:\textbf{a}]
  [, solid node, small_edge_label={below}{$Pr(neg|yes)=0.4$}, label=right:\textbf{b}]
  ]
  [, hollow node, big_edge_label={left}{$Pr(no)=0.9$}
  [, solid node, small_edge_label={above}{$Pr(pos|no)=0.2$}, label=right:\textbf{c}]
  [, solid node, small_edge_label={below}{$Pr(neg|no)=0.8$}, label=right:\text{d}]
  ]
  ]
  %% \node [font=\itshape] at (!r |- !r1) {Governo};
\end{forest}
\end{document}