What is the error in an observed direction for the situations noted? $(10$ points$)$

a$)$ setting a total station $7$ mm to the side of a tack on a $30-m$ sight.

b$)$ lining in the edge $($instead of center$)$ of an $\frac{2}{16}-in.$ diameter chaining pin at $300$ ft $.$

c$)$ sighting the edge $($instead of center$)$ of a $2\mathrm{.}3-cm$ diameter range pole $200$ m $.$

d$)$ sighting a target at the top of a $3-m$ range pole that is ${15}^{\text{'}}$ off$-$level on a $100-m$ sight.