Determine point that give most accurate reading when measuring resistance

The question is at this link <a href="https://www.iitjee.org/iit-question-papers/iit-jee-2005-main/iit-jee-2005-physics-main-3.html" target="_blank" rel="nofollow noopener noreferrer">IIT 2005 Main Paper Physics : IIT JEE 2005 Physics Main Question Paper and Solutions</a> . Since the solution cannot uploaded i print screen my solution and uploaded at this 2 website #-Link-Snipped-# and #-Link-Snipped-# . I would like to ask for opinion will my answer also correct? A person may be measuring the length using a ruler that is not accurate, it may differ from the actual value by a negative length or positive length.