Correct Answer: D. Random errors
Solution:
Random errors, also known as accidental errors, are unpredictable variations in measurements that occur without a recognizable pattern. While they can be minimized by repeating measurements and applying statistical methods, they cannot be completely eliminated. Systematic errors (instrumental, personal, natural causes) can typically be identified and corrected.
Correct Answer: C. 1/25000
Solution:
The 1:25,000 scale is a standard topographical map scale used for various purposes, including forestry. It provides a good balance of detail and area coverage, making it suitable for managing and planning forest areas.
Correct Answer: C. 1 cm = 86.95 m
Solution:
First, calculate the Shrinkage Factor (SF).
SF = Shrunk Length / Original Length = 4.6 m / 5 m = 0.92.
The shrunk scale is found by dividing the original scale's ground distance by the SF.
New ground distance = 80 m / 0.92 = 86.9565 m.
So, the new scale is 1 cm = 86.95 m.
Correct Answer: B. 0.01 mm
Solution:
This describes a retrograde Vernier scale. The value of one main scale division (s) is 0.1 mm. The value of one Vernier scale division (v) is (11/10) * 0.1 mm = 0.11 mm. The least count (LC) is the difference between one Vernier division and one main scale division: LC = v - s = 0.11 mm - 0.1 mm = 0.01 mm.
Correct Answer: A. Decrease
Solution:
The representative fraction (RF) represents the ratio of map distance to ground distance. A larger denominator (e.g., 1/50,000) means 1 unit on the map represents a larger distance on the ground compared to a smaller denominator (e.g., 1/5,000). This results in a smaller scale map, which covers a larger area with less detail. Therefore, as the denominator increases, the scale decreases.
Correct Answer: C. 1 cm = 86.95 m
Solution:
First, calculate the Shrinkage Factor (SF).
SF = Shrunk Length / Original Length = 4.6 m / 5 m = 0.92.
The shrunk scale is found by dividing the original scale's ground distance by the SF.
New ground distance = 80 m / 0.92 = 86.9565 m.
So, the new scale is 1 cm = 86.95 m.
Correct Answer: B. Intersect at the center of the Earth
Solution:
In geodetic surveying, the curvature of the Earth is considered. Plumb lines indicate the direction of gravity, which points towards the Earth's center of mass. Therefore, lines of gravity from two different points will converge and intersect at the center of the Earth. In plane surveying, they are assumed to be parallel.
Correct Answer: D. 540
Solution:
For a triangle on a spherical surface, the sum of the interior angles is always greater than 180° and less than 540°. This is a key difference from a plane triangle, where the sum is exactly 180°.
Correct Answer: C. 15
Solution:
In an extended vernier, 'n' divisions of the vernier scale are equal to (2n - 1) divisions of the main scale. In this case, n = 8. Therefore, the number of main scale divisions is (2 * 8) - 1 = 16 - 1 = 15.
Correct Answer: D. 771450
Solution:
First, find the original area on the map before it shrunk. The shrunk area factor is (Shrinkage Factor)² = (0.9)² = 0.81.
Original Map Area = Shrunk Map Area / Shrunk Area Factor = 250 cm² / 0.81 ≈ 308.64 cm².
Next, use the original scale to find the field area. The area scale is (50 m/cm)² = 2500 m²/cm².
Original Field Area = Original Map Area × Area Scale Factor = 308.64 cm² × 2500 m²/cm² ≈ 771,605 m². The closest answer is 771,450.
Correct Answer: B. Cadastral survey
Solution:
Cadastral surveys are specifically conducted to determine and define land ownership and property boundaries for legal purposes, including for taxation and property deeds.
Correct Answer: D. retrograde vernier
Solution:
A retrograde vernier has its divisions marked in the opposite direction to the main scale. On this type of vernier, the divisions are slightly larger than the main scale divisions.
Correct Answer: D. 1 : 200,000
Solution:
To find the Representative Fraction (RF), both units must be the same.
First, simplify the given scale: 10 cm = 20 km is the same as 1 cm = 2 km.
Now, convert km to cm: 1 km = 100,000 cm, so 2 km = 200,000 cm.
The scale is 1 cm on the map equals 200,000 cm on the ground. Therefore, the RF is 1 : 200,000.
Correct Answer: A. direct vernier
Solution:
This is the definition of a direct vernier. The divisions on the vernier scale are slightly smaller than the divisions on the main scale, and it is read in the same direction as the main scale.
Correct Answer: C. 0.25
Solution:
This is a standard convention in drafting and cartography. It is based on the limit of human vision, where a deviation smaller than 0.25 mm is generally not discernible to the naked eye. This value is also known as the limit of plotting accuracy.