An electricity company charges the same fixed amount for each unit of electricity used - Edexcel - GCSE Maths - Question 9 - 2022 - Paper 3

To find the gradient of the line, we use the formula:

ext{Gradient} = rac{ ext{Change in Cost}}{ ext{Change in Number of Units}}

From the graph, we can select two points:

• Point 1 (0 units, £0)
• Point 2 (100 units, £20)

Calculating the differences:

• Change in Cost = £20 - £0 = £20
• Change in Number of Units = 100 - 0 = 100

Now substituting these into the formula gives:

ext{Gradient} = rac{20}{100} = 0.2

Thus, the gradient of the straight line is 0.2.