Leo wants to estimate the number of trout in a lake.
He catches a sample of 30 trout, marks them and releases them back into the lake.
The next day, he takes a second sample of 50 trout.
6 of these trout have been marked.
Work out an estimate for the number of trout in the lake.
Write down an assumption you have made.
20 exam-style questions on OCR GCSE Maths Capture Recapture. Each one has a worked solution and a mark scheme showing where the marks go.