I have a chart with y axis 80 to 100. I want to mark the line at 95 with a different color from the rest of the chart grid lines. Is this possible?
Yup, that describes how to do the first method I referred too.
There are two possible ways to go about doing so. The first is to add data in the data set to have a graph at 95. Secondly, you can draw a line on your graph and colour it a different colour.
I am looking forward to learning a more eloquent method.