Illinois Professional Land Surveyor
Examination Advanced Practice Exam 2026
| 100 Questions & Answers with Detailed
Rationales | Complete Exam Prep & Study
Guide
1. A closed traverse has measured interior angles whose sum differs from the
theoretical sum by 18 seconds. What is the most appropriate first step?
A. Distribute the error arbitrarily among the distances
B. Reject the traverse immediately
C. Determine whether the angular misclosure is within the allowable tolerance
and then apply an appropriate angular adjustment
D. Adjust only the final angle
Answer: C. Determine whether the angular misclosure is within the allowable
tolerance and then apply an appropriate angular adjustment
Rationale: A traverse should first be evaluated against the applicable precision
standard. If the misclosure is acceptable, the angular error can be distributed
using a defensible adjustment procedure before adjusting the coordinate
components.
, 2. In a least-squares adjustment of a surveying network, an observation with a
very small standard deviation generally receives:
A. A smaller weight
B. No weight
C. A larger weight
D. A negative weight
Answer: C. A larger weight
Rationale: In weighted least squares, observations with smaller variances are
considered more precise and therefore receive greater weight, commonly
expressed as proportional to the inverse of variance.
3. A total station measures a slope distance of 1,250.000 ft and a vertical
angle of 3°30′ above horizontal. Ignoring curvature and refraction, which
value is closest to the horizontal distance?
A. 1,247.674 ft
B. 1,247.670 ft
C. 1,250.000 ft
D. 1,253.000 ft
Answer: B. 1,247.670 ft
Rationale: Horizontal distance equals slope distance multiplied by the cosine of
the vertical angle. Thus, 1,250 cos(3°30′) is approximately 1,247.67 ft.
4. A benchmark has an accepted elevation of 742.315 ft. A backsight of 5.284
ft is observed. What is the height of instrument?
A. 737.031 ft
B. 747.599 ft
C. 742.315 ft
D. 752.883 ft
Answer: B. 747.599 ft
,Rationale: Height of instrument equals known elevation plus backsight: 742.315
+ 5.284 = 747.599 ft.
5. Which observation is most directly affected by prism constant errors when
using an electronic distance measurement system?
A. Horizontal angle only
B. Vertical angle only
C. Measured distance
D. Instrument centering only
Answer: C. Measured distance
Rationale: A prism constant represents an offset between the electronic distance
measurement reference and the physical prism geometry. An incorrect constant
introduces a systematic distance error.
6. A surveyor establishes a boundary corner using GNSS observations. Which
factor can cause a significant difference between a GNSS ellipsoidal height
and an orthometric elevation?
A. Prism constant
B. Geoid separation
C. Tape temperature
D. Horizontal angle closure
Answer: B. Geoid separation
Rationale: GNSS primarily determines ellipsoidal height relative to an ellipsoid,
while orthometric height is related to mean sea level through the geoid. The
geoid model supplies the relationship between them.
7. A line has a bearing of N 35°20′ E. What is its azimuth?
A. 35°20′
B. 35°20′
C. 144°40′
D. 324°40′
, Answer: B. 35°20′
Rationale: In the northeast quadrant, a quadrant bearing measured north
toward east is numerically identical to the azimuth measured clockwise from
north.
8. What is the azimuth of S 42°15′ W?
A. 42°15′
B. 137°45′
C. 222°15′
D. 317°45′
Answer: C. 222°15′
Rationale: A southwest quadrant bearing converts to azimuth by adding 180° to
the bearing angle: 180° + 42°15′ = 222°15′.
9. A line has an azimuth of 276°40′. Its quadrant bearing is:
A. N 83°20′ W
B. S 83°20′ W
C. S 6°40′ W
D. N 6°40′ W
Answer: B. S 83°20′ W
Rationale: An azimuth between 270° and 360° lies in the northwest quadrant.
Subtracting the azimuth from 360° gives 83°20′, and the corresponding bearing
is S 83°20′ W when expressed from the south reference.
10.The principal purpose of a backsight in differential leveling is to:
A. Determine horizontal distance
B. Establish magnetic declination
C. Establish the height of instrument from a known elevation
D. Determine the prism constant
Examination Advanced Practice Exam 2026
| 100 Questions & Answers with Detailed
Rationales | Complete Exam Prep & Study
Guide
1. A closed traverse has measured interior angles whose sum differs from the
theoretical sum by 18 seconds. What is the most appropriate first step?
A. Distribute the error arbitrarily among the distances
B. Reject the traverse immediately
C. Determine whether the angular misclosure is within the allowable tolerance
and then apply an appropriate angular adjustment
D. Adjust only the final angle
Answer: C. Determine whether the angular misclosure is within the allowable
tolerance and then apply an appropriate angular adjustment
Rationale: A traverse should first be evaluated against the applicable precision
standard. If the misclosure is acceptable, the angular error can be distributed
using a defensible adjustment procedure before adjusting the coordinate
components.
, 2. In a least-squares adjustment of a surveying network, an observation with a
very small standard deviation generally receives:
A. A smaller weight
B. No weight
C. A larger weight
D. A negative weight
Answer: C. A larger weight
Rationale: In weighted least squares, observations with smaller variances are
considered more precise and therefore receive greater weight, commonly
expressed as proportional to the inverse of variance.
3. A total station measures a slope distance of 1,250.000 ft and a vertical
angle of 3°30′ above horizontal. Ignoring curvature and refraction, which
value is closest to the horizontal distance?
A. 1,247.674 ft
B. 1,247.670 ft
C. 1,250.000 ft
D. 1,253.000 ft
Answer: B. 1,247.670 ft
Rationale: Horizontal distance equals slope distance multiplied by the cosine of
the vertical angle. Thus, 1,250 cos(3°30′) is approximately 1,247.67 ft.
4. A benchmark has an accepted elevation of 742.315 ft. A backsight of 5.284
ft is observed. What is the height of instrument?
A. 737.031 ft
B. 747.599 ft
C. 742.315 ft
D. 752.883 ft
Answer: B. 747.599 ft
,Rationale: Height of instrument equals known elevation plus backsight: 742.315
+ 5.284 = 747.599 ft.
5. Which observation is most directly affected by prism constant errors when
using an electronic distance measurement system?
A. Horizontal angle only
B. Vertical angle only
C. Measured distance
D. Instrument centering only
Answer: C. Measured distance
Rationale: A prism constant represents an offset between the electronic distance
measurement reference and the physical prism geometry. An incorrect constant
introduces a systematic distance error.
6. A surveyor establishes a boundary corner using GNSS observations. Which
factor can cause a significant difference between a GNSS ellipsoidal height
and an orthometric elevation?
A. Prism constant
B. Geoid separation
C. Tape temperature
D. Horizontal angle closure
Answer: B. Geoid separation
Rationale: GNSS primarily determines ellipsoidal height relative to an ellipsoid,
while orthometric height is related to mean sea level through the geoid. The
geoid model supplies the relationship between them.
7. A line has a bearing of N 35°20′ E. What is its azimuth?
A. 35°20′
B. 35°20′
C. 144°40′
D. 324°40′
, Answer: B. 35°20′
Rationale: In the northeast quadrant, a quadrant bearing measured north
toward east is numerically identical to the azimuth measured clockwise from
north.
8. What is the azimuth of S 42°15′ W?
A. 42°15′
B. 137°45′
C. 222°15′
D. 317°45′
Answer: C. 222°15′
Rationale: A southwest quadrant bearing converts to azimuth by adding 180° to
the bearing angle: 180° + 42°15′ = 222°15′.
9. A line has an azimuth of 276°40′. Its quadrant bearing is:
A. N 83°20′ W
B. S 83°20′ W
C. S 6°40′ W
D. N 6°40′ W
Answer: B. S 83°20′ W
Rationale: An azimuth between 270° and 360° lies in the northwest quadrant.
Subtracting the azimuth from 360° gives 83°20′, and the corresponding bearing
is S 83°20′ W when expressed from the south reference.
10.The principal purpose of a backsight in differential leveling is to:
A. Determine horizontal distance
B. Establish magnetic declination
C. Establish the height of instrument from a known elevation
D. Determine the prism constant
