Given data:
a)
The expression for the mean number of drivers expected to be wearing seat belts is,
[tex]\begin{gathered} m=\frac{89}{100}\times140 \\ =124.6 \\ \approx125 \end{gathered}[/tex]The expression for the standard deviation of drivers expected to be wearing seat belts is,
[tex]\begin{gathered} s=\sqrt[]{(0.89)(1-0.89)\times140} \\ =\sqrt[]{13.706} \\ =3.702 \end{gathered}[/tex]Thus, the mean number of drivers expected to be wearing seat belts is 125, and the standard deviation of drivers expected to be wearing seat belts is 3.702.