A plumber charges a fixed call-out fee plus a fixed hourly rate for the time spent on a job.
A job lasting 2 hours costs £115.
A job lasting 5 hours costs £250.
The plumber's charge, £CCC, for a job lasting t t\,t hours is modelled by a straight line.
Find an equation for C C\,C in terms of ttt.
Interpret the gradient and the vertical intercept of your model in the context of the question.
143 exam-style questions on OCR A Level Maths 1.3 Coordinate Geometry in the x-y Plane, covering 1.3.1 Straight lines, 1.3.2 Parallel and perpendicular lines, 1.3.3 Straight line models, 1.3.4 Coordinate geometry of a circle, 1.3.5 Centre and radius by completing the square, 1.3.6 Circle properties, 1.3.7 Parametric equations of curves (A-level only), 1.3.8 Parametric equations in context (A-level only), and 1.3 Coordinate Geometry in the x-y Plane. Each one has a worked solution and a mark scheme showing where the marks go.