To now how many had a score under 66, we have to calculate the following probability
[tex]P(X<66)=P(Z<\frac{66-81}{5})=P(Z<-3)=0.0013[/tex]So the amount of people that had a score under 66 is
[tex]4502\cdot0.0013=5.86\approx6[/tex]So 6 people get a score under 66
