A 30m chain was tested before starting the day work and was found 20cm is too short. After measuring a length of 1250m, the chain was to be tested and found to be 10cm is too long at the end of ....
1 Answer

(1) Error before starting the day work = 20cm too short = -0.2m

Error after measuring a length of 1250m it is found 10cm long = 0.1 m

Average error= $\frac{(-0.2+0.1)}{2}$=-0.05m

L1= 30 - 0.05 = 29.95m

Measured distance =1250m

Correct length = $\frac{L1}{L}$× measured distance =$\frac{29.95}{30}$×1250 = 1247.92m

Correct length = 1247.92m

(2) Error at the end of the day work the chain found to be 30cm too long = 0.3m

Average error=$\frac{(-0.05+0.3)}{2}$ =-0.125m

L1= 30 + 0.125m= 30.125m

Measured distance =2648 – 1250 =1398m

Correct length = $\frac{L1}{L}$× measured distance =$\frac{30.125}{30}$×1398 = 1403.83m

Total true length = 1247.92+1403.83 =2651.75m

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