A sixth form college has 84 students in Year 12 and 56 students in Year 13.
The head teacher selects a stratified sample of k k\,k students, where k k\,k is a positive multiple of 5 and k≤140k\le 140k≤140, stratified by year group.
Describe how this sample could be taken, in terms of kkk.
59 exam-style questions on Edexcel A Level Maths Data Collection, covering 1.1 Populations and Samples, 1.2 Sampling, 1.3 Non-Random Sampling, 1.4 Types of Data, and 1.5 The Large Data Set. Each one has a worked solution and a mark scheme showing where the marks go.