# Civil Engineering - UPSC Civil Service Exam Questions - Discussion

44.

A 20 m chain was found to be 10 cm too long after chaining a distance of 2000 m. It was found to be 18 cm too long at the end of the day's work after chaining a total distance of 4000 m. What is the true distance if the chain was correct before the commencement of the day's work ?

 [A]. 3962 m [B]. 4019 m [C]. 3981 m [D]. 4038 m

Explanation:

No answer description available for this question.

 Parushrut said: (Jun 25, 2016) Please describe it.

 Rahul Chopra said: (Sep 15, 2016) L = 20m L' = 20 + {(0 + 0.10)/2} = 20.05 mean elongation. Measured lngth = 2000m(M.L). True length(T.L) = L'/L * M.L. T.L = 20.05/20 * 2000. = 2005m. 2nd part 2nd M.L = 4000 - 2000 = 2000m. mean elongation for part 2nd = 20{(.10 + .18)/2} = 20.14. T.L = 20.14/20 * 2000(2nd M.L). = 2014m. Therefore, the True distance = 2005 + 2014 = (part1 + part2) = 4019m.

 Rahul Guleria said: (Apr 2, 2017) T*T' = F' * F. F' = 20(.10+.18/2) = 20.14, Now T * 20 = 20.14 * 4000. T = 20.14 * 4000/20 = 4029. So the answer is B.