The statement 'Amy is 2 years older than Colin' represents a constant difference and is not a proportional relationship since proportions require quantities to change at a consistent rate.
The statement 'Amy is 2 years older than Colin' suggest a constant difference in age between two individuals. In mathematics, this relationship is not proportional because being proportional implies that the quantities involved increase or decrease at the same rate. In contrast, a constant difference means no matter how old Colin gets, Amy will always be exactly 2 years older. An example of a proportional relationship would be if Amy was always twice as old as Colin, which is not the case here.
To understand further, consider another example, 'Beth: The general proportions of the building can be expressed mathematically as X = Y x 2 + 1.' This shows a proportional relationship where X increases as Y increases, according to the formula. However, Amy and Colin's ages do not follow a formula that creates a ratio, but instead maintain a constant age difference.