Question

In a closed traverse ABC, the following readings were taken: If station A is free from local attraction, correct bearing of CB is: 

• A. \(280^\circ \)
• B. \(279^\circ \)
• C. \(276^\circ \)
• D. \(277^\circ \)

Hint:

In a closed traverse, if one station is known to be free from local attraction, bearings of other stations should be corrected based on that reference.

Answer 1

The Correct Option is D

Step 1: Understanding the concept of local attraction correction. In a closed traverse, local attraction affects the bearings of stations influenced by external magnetic interference. If station A is free from local attraction, the correct bearings of other stations must be adjusted accordingly. 
Step 2: Checking the bearing of CA. From the given table, - Fore bearing of CA = \(227^\circ\) - Back bearing of CA = \(49^\circ\) (which is \(227^\circ - 180^\circ\)) This confirms station A has no local attraction, so corrections need to be applied to BC. 
Step 3: Correcting the bearing of BC. For an unaffected station, \[ \text{Back Bearing}  = \text{Fore Bearing}  \pm 180^\circ. \] Checking BC, \[ \text{Back Bearing of BC} = 277^\circ. \] Thus, \[ \text{Fore Bearing of CB}  = 277^\circ. \]