GCSE (9-1) - An application of straight line graphs - Celsius-Fahrenheit graph

This is an exam-style question in which a factorised equation is given for Celsius in terms of Fahrenheit. It's aimed at students capable of achieving grade 4 upwards. They will need to expand the equation to work out both the gradient and Celsius intercept of the equation, use the equation to find points on the graph and then plot it accordingly. They are then required to take readings from the graph, both in Celsius and Fahrenheit, and then check these with the same results using the equation. To find the Fahrenheit result they will need to rearrange the equation so that Fahrenheit is the subject.

Fully worked answers are provided. The graph can be constructed and plotted on ordinary graph paper but if you would prefer to use a graph with pre-printed axes then a software-generated JPG file has been provided. Two of the points required to plot the graph come out to whole numbers so it should not be too difficult for students to plot it with reasonable accuracy. The software-plotted graph was originally created using GRAPH, a freely available open-source program. TES does not support upload of GRAPH data files but if you would like a copy of it showing the plotted graph then please email me at kevin_alderson@yahoo.co.uk. Please be assured that I will only use it for this purpose. I will not share your email with anyone else, nor will I use it for promotion of my resources or any other reason.