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===About Direct Proportionality===
: A [[Scatter Graph|scatter graph]] showing a '''directly proportional''' relationship has line with a [[linear]] [[gradient]] that passes through zero, (it has a [[y-intercept]] of zero).
: On a [[proportional]] [[Scatter Graph|scatter graph]] when one [[variable]] doubles, the other doubles or when one triples the other triples.
: When two variables are '''directly proportional''' when any value for y is divided by its corresponding value for x it will always give a constant value.
: Two variables are said to be '''directly proportional''' when they always vary by the same ratio.
===Exam Marks===
: Straight line [1 mark]
: Passing through zero / passing through the origin [1 mark]
===Examples===
:[https://www.amazon.co.uk/gp/product/019835939X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=019835939X&linkCode=as2&tag=nrjc-21&linkId=57e96876985fc39b1a3d8a3e3dc238b6 ''Directly proportional, pages 158-159, 282, GCSE Physics; Third Edition, Oxford University Press, AQA '']
====Edexcel====