Given a binary search trees for a set of $n=5$ keys with the following probabilities $:$
$\begin{array}{|l|l|l|l|l|l|l|}\hline \text{i} & \text{0} & \text{1} & \text{2} & \text{3} & \text{4} & \text{5} \\\hline \text{$p_i$} & \text{-} & \text{0.15} & \text{0.10} & \text{0.05} & \text{0.10} & \text{0.20} \\\hline \text{$q_i$} & \text{0.05} & \text{0.10} & \text{0.05} & \text{0.05} & \text{0.05} & \text{0.10} \\\hline \end{array}$
The expected optimal cost of the search is
- $2.65$
- $2.70$
- $2.75$
- $2.80$