A scientist is testing four different materials—Rubber, Steel, Wood, and Glass—in pairs to see how they interact. Every material must be tested against every other material once.
List all the pairs of materials that will be tested.
After the tests, the materials are ranked from 1st to 4th based on their durability. List all the possible rankings of the materials.
125 exam-style questions on OCR GCSE Maths Systematic Listing. Each one has a worked solution and a mark scheme showing where the marks go.