Figure    11B IN  ANSWERING  QUESTION  11-18,  REFER  TO FIGURE  11B. 11-18. What  is  the  target  reading? 1. 8.128 ft 2. 9.120 ft 3. 9.128 ft 4. 279.0    ft 11-19. In  leveling,   which of the following  statements  best  defines height  of  instrument  (HI)? 1. 2. 3. 4. The  elevation  of  the horizontal  line  of  sight The vertical distance from the horizontal  axis  of  the telescope to a point on the ground directly below the instrument The vertical distance between the  reference  datum  and  the horizontal line of sight The elevation of the reference datum minus the backsight rod reading 11-20. In determining the elevation of an unknown point,   what arithmetic operation should you apply to the HI and FS? 1. Addition 2. Subtraction 3. Multiplication 4. Division 11-21. By using the technique of balancing  shots,   you  can  eliminate which  of  the  following  effect(s) in  differential  leveling? 1. Instrumental  error 2. Curvature of the earth’s surface 3. Atmospheric refraction 4. All of the above 11-22. When turning points are being set up  in  ordinary  precision  leveling, what should be the maximum distance between the instrument and a TP? 1. 200 ft 2. 300 ft 3. 600 ft 4. 1,000 ft 11-23. When turning points are located in sandy  soil,   you must set the level rod on a base. Which of the following  bases  is  an  acceptable choice? 1. A turning point plate 2. A turning point pin driven into the soil 3. A marlin spike driven into the soil 4. Each of the above 11-24. The original level run is rapidly rerun as a check in what type of leveling  procedure? 1. Three-wire 2. Cross-section 3. Profile 4. Flying 77