Question

5. A chain was tested before starting the survey and was found to be
20 m. At the end of the survey it was tested again and found to be
20.12 m. Area of the plan of the field drawn to a scale of
10 mm = 6 m, was 5040 mm2. Find the true area of the field in m2​

Answer 1

Answer:

1cm = 6m

1cm2 = 36m2

Area of plank = 50.4 cm2

Measured area of field = 50.4 * 36

= 1814.4m2

Incorrect length of chain, L’ = (20+20.12)/2

= 20.06m

L = 20m

True area = (L’/L)2 * measured area

= (20.06/20)2 * 1814.4

= 1825.3m2

1 hectare = 10,000m2

= 0.1825 hectare