The graph below shows the trend in the number of cases of people infected with the coronavirus in a particular country. Jamie claims that the trend shown is approximated by a linear equation of the form $y = 320x$, where $x$ is the number of days and $y$ is the number of infections. Explain why she is wrong.

1. Identify why the graph does not support the stated linear model

The vertical axis is not a normal linear scale, since $10,100,1000,10000$ are equally spaced. It is a logarithmic scale. Therefore, the dashed straight line on the graph is not evidence that $y$ is directly proportional to $x$, so the trend cannot be approximated by $y=320x$ from this graph.