A scientist wants to estimate the population of beetles in a field. They capture 120 beetles, mark them with a small dot of paint and release them. The next day, they capture a second sample of 100 beetles and find 30 are marked.
Work out an estimate for the population of beetles in the field.
Write down any assumptions 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.