The length of a survey line was measured with a 20 m chain and was found to be equal to 1200 m. If the length again measured with 25 m chain it is 1212 m. On comparing the 20 m chain with the test gauge, it was found to be 1 decimeter too long. Find the actual length of 25 m chain used.

Correct Answer: 24. 88 m
Incorrect length of 20 m line is 20+0.10 = 20.10 m. True length of line = 1200×(20.10/20) = 1206 m. Actual or True length of 25 m chain = (1206×25)/1212 = 24.88 m.