Higher June 2022 Paper 3 Q8
8 An electricity company charges the same fixed amount for each unit of electricity used.
David uses this graph to work out the total cost of the electricity he has used.
(a) Work out the gradient of the straight line. (2)
(b) What does the gradient of this line represent? (1)
| Answer | Mark | Mark scheme |
|---|---|---|
| 0.14 | M1 | for a method to find the gradient, eg \(14 \div 100\) using readings from the graph, at least one correct or for an answer of \(0.14x\) |
| A1 | for answer in the range 0.135 to 0.145 or ft correct readings from the graph |
Additional guidance
Must use the scales on the graph
May be expressed as a fraction
| Answer | Mark | Mark scheme |
|---|---|---|
| Cost per unit of electricity | C1 | for a correct explanation Acceptable examples eg cost of each unit (of electricity) rate of change of cost with units of electricity used cost per unit of electricity each unit costs 14p average cost charged for each unit of electricity used Not acceptable examples cost of how many units used costs in pounds per number of units used how much the cost of electricity goes up the relationship of cost and number of units used how steep it is |