In order to calculate the expected value in the first three prizes, let's first calculate the probability of a $50 certificate being drawn:
[tex]P=\frac{3}{4+5+3}=\frac{3}{12}[/tex]Now, to find the expected value, we multiply the probability by the number of times the event is occurring:
[tex]\begin{gathered} E(x)=P\cdot n \\ E(x)=\frac{3}{12}\cdot3=\frac{9}{12}=\text{0}.75 \end{gathered}[/tex]Therefore the correct option is D.
