SOLUTION
Given
[tex]P(E)=0.4,P(F)=0.5,P(E\text{ and F)}=0.2[/tex]
Using the rule of probability it follows:
[tex]P(E\text{ or F)}=P(E)+P(F)-P(E\text{ and F)}[/tex]
Substituting values gives
[tex]\begin{gathered} P(E\text{ or F)}=0.4+0.5-0.2 \\ P(E\text{ or F)}=0.7 \end{gathered}[/tex]
Therefore the answer is P(E or F)=0.7
