An angle is observed 6 times from directions on both face left and face right. The directions are measured with a Total Station instrument with a DIN of 5. The prisms are well defined and placed on an optical plummet tribrach with an estimated error of 2mm. The instrument is in good adjustment and centered over the station with an estimated error of 1mm. The horizontal distances from the instrument to the backsight and foresight targets are 185.002m and 137.194m respectively. The averaged angle between the targets has been calculated as 23 08 13. Calculate the total standard deviation of the mean angle, and provide your answerin sexagesimal system to the nearest 1 second. need accurate answer...with steps