40 likes | 55 Views
Calculate the cost of a plumber's call-out based on hourly rates and determine why the charge is not directly proportional. Analyze the graph to understand the intercept and gradient. Explore the advantages and disadvantages of using a graph for job charges.
E N D
Nuffield Free-Standing Mathematics ActivityPlumber’s call-out
24 hour Plumber Call-out £20 Hourly rate £40 How much will it cost if the plumber takes 2 hours?
Plumber's charges 240 220 200 180 160 140 120 100 80 60 40 20 0 0 1 2 3 4 5 Hours The plumber charges £ 20 + £40 per hour. It costs £20 before she does anything. It costs £100 for a 2 hour job. What amounts should go in the gaps in the table? Charge (£)
Plumber’s call-out At the end of the activity • Why was the plumber’s charge not directly proportional to the time she worked? • How can you tell from the graph that it is not directly proportional? • What does the intercept tell you about the plumber’s charge? • What does the gradient tell you? • What are the advantages of using a graph to find charges for jobs? • What are the disadvantages?