Weber's law explains the perceived differentiation between similar stimuli of varying intensities. The difference is perceives depending upon proportion, not upon the amount.
Example: For a computer priced at $1ooo, a person may consider spending $200 for additional memory to be too much, while if the same amount has to be spent to renovate a house worth $300,000, it will seem like nothing.
Answer 2
1. Provides with a better market place, same brand may then be advertised in different markets based on the perceived benefits of customers.