A river contains five different types of fish.
There are an estimated 480 Minnows, 240 Grayling, 180 Barbel, 120 Gudgeon and 180 Trout.
Lewis wishes to investigate the health of the fish in the river.
He decides to take a sample of 100 fish.
Give a reason why stratified random sampling cannot be used.
Explain how a sample of size 100 could be taken to ensure that the estimated populations of each type of fish are fairly represented.
You should state the name of the sampling method used.
23 exam-style questions on Edexcel AS 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.