Direct and inverse proportion
Distinguish direct and inverse proportion by checking ratios and products.
Meaning
In direct proportion, one quantity is a constant multiple of the other. In inverse proportion, their product is constant.
Example
At 800 won each, n items cost 800n won: direct proportion. Sharing 24 items among n people gives 24/n items per person: inverse proportion. Equal sharing gives n×(each share)=24, so each share is 24/n. Here n is a positive integer; if items cannot be split, also check that n divides 24. Two quantities increasing together need not be directly proportional. A fixed starting fee can prevent a constant ratio.
Practice for this concept
Scope and references
Topics
Quantities varying at a constant ratio, quantities with a constant product
Learning goal
Distinguish direct and inverse proportion by checking ratios and products.
Helpful background
Calculate and compare ratios and products of corresponding quantities.
Direct and inverse proportion
These ordinary choice questions provide limited practice in this concept. They do not establish independent solution, full-concept performance, or mastery.