Answer:
9 is the correct answer to the given question .
Step-by-step explanation:
AS mention in the question the random variable x is the number of vehicles that passing through the intersection in the 30-minute .So we concluded that it is normal distribution because in the normal distribution the variable values are divided .
In the Normal distribution
[tex]Mean \ number\ =\ Expected\ value\ \\Here Mean number\ =\ 9[/tex]
Therefore the Expected value =9.