==Key Stage 4=====Meaning===When two [[variable]]s are [[proportional]] their values have a constant [[ratio]]. ===About Proportional Graphs===: A [[Scatter Graph|scatter graph]] showing a [[proportional]] relationship has a [[linear]] [[gradient]].: On a [[proportional]] [[Scatter Graph|scatter graph]] when one [[variable]] increases, the other increase or when one increases the other decreases.: A [[proportional]] graph may have a non-zero [[y-intercept]].: If the [[Line of Best Fit|line of best fit]] has a [[y-intercept]] of zero then it is called '#Redirect [[Directly Proportional|directly '''proportional''']]'.===Examples==={| class="wikitable"|-|[[File:ProportionalSketchGraph1.png|center|200px]]|[[File:ProportionalSketchGraph2.png|center|200px]]|[[File:DirectlyProportionalSketchGraph.png|center|200px]]|-| style="height:20px; width:200px; text-align:center;" |This [[Scatter Graph|scatter graph]] shows a [[linear]] relationship that is [[proportional]] where x increases, y increases. <math>y = mx + c</math> Where m, the [[gradient]], is positive.| style="height:20px; width:200px; text-align:center;" |This [[Scatter Graph|scatter graph]] shows a [[linear]] relationship that is [[proportional]] where x increases, y decreases. <math>y = mx + c</math> Where m, the [[gradient]], is negative.| style="height:20px; width:200px; text-align:center;" |This [[Scatter Graph|scatter graph]] shows a [[linear]] relationship that is [[Directly Proportional|directly proportional]] where x doubles, y doubles. <math>y = mx</math> Where m, the [[gradient]], is positive.|}