Mathematics for IGCSE & O level - Graphs In Practical Situations (Section 1 - No. 38)
If a conversion graph results in a straight line, this means:
The relationship between the units is non-linear.
The units are not related.
There is a direct, proportional relationship between the units.
The conversion is impossible.
Explicación
A straight line implies a constant ratio of change between the two units, indicating a direct proportional relationship.