Question

The length of a line measured with a 20 m chain was found to be 250 m. Calculate the true length of the line if the chain was 10 cm longer.
1. 252.25 m
2. 251.25 m
3. 225.25 m
4. 221.25 m

Answer 1

Correct Answer - Option 2 : 251.25 m

Concept:

\(True\;length\;line = \frac{{l'}}{l} \times measured\;length\\ \)

Where, 

 l' is corrected length of chain

 l is actual length of chain

Calculation:

True length of line (L) = ?

Actual length of chain (l) = 20 m

Measured length of line (L') = 250 m

Corrected length of chain (l') = 20.1 m 

So, we know

\(True\;length\;line = \frac{{l'}}{l} \times measured\;length\\ \)

\(\Rightarrow L = \frac{{20.1}}{{20}} \times 250\)

∴ L= 251.25 m