Problem $6$

How many meters long does a horizontal distance have to be for the combined correction for earth curvature and refraction to become equal or larger than twelve centimeters $(0\mathrm{.}12m)?$

Problem $7$

A TS is used to measure the difference of elevation between points A and $B.$ The elevation of point $A$ is ${5890\mathrm{.}11}^{\text{'}}.$ The instrument height is ${5\mathrm{.}88}^{\text{'}}.$ The target$/$prism height is ${4\mathrm{.}26}^{\text{'}}.$ The zenith angle is $141{56}^{\text{'}}{40}^{\text{'}\text{'}}.$ The measured slope distance is ${905\mathrm{.}55}^{\text{'}}($short distance$).$ What is the elevation of point B$?$