Creating the chart With the two columns highlighted create a new chart:
Insert→Chart→Chart type=XY(Scatter)
Make sure you select the XY(Scatter) NOT Chart type=Line
If you select all the default options your chart will look something like this:
Default Excel chart
This won't get you many marks, you will have to change just about everything on the graph to bring it up to an acceptable standard.
Below is an improved version of the graph that would be suitable if you have a colour printer. For a black and white printer get rid of the blue squares completely and make the points and line black as well.
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