Straight-Line Graphs

Demonstrating straight-line graphs using mobile phone contracts Inside Maths builds on the success of the series Maths 4 Real.

Dave thinks he has a fantastic deal on his mobile phone: £20 per month with 1000 texts and 600 minutes of talk time. But he did have to pay for the phone? Fran thinks maybe an 18-month contract at £35 per month would have been better.

As Dave heads off to find out what some students think, Fran, using vivid graphics, gives an overview of straight-line graphs and plots a graph for the pay-as-you-go deal.

Dave and the students quickly work out that over 18 months the pay-as-you-go deal is cheaper than the contract, but what happens when you factor in 5p a day every time you use the internet?

Again, Fran uses straight-line graphs and their gradients to see how many days a month Dave can use the internet on his phone and still be better off.

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