A lake contains five different types of fish.
There are an estimated 320 Roach, 240 Bream, 160 Rudd, 200 Tench and 480 Carp.
John wishes to investigate the health of the fish in the lake.
He decides to take a sample of 140 fish.
Give a reason why stratified random sampling cannot be used.
Explain how a sample of size 140 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.
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.