Amara wants to find an estimate for the number of ladybirds in a greenhouse.
She catches 80 ladybirds and marks their shells with a small dot of paint. These ladybirds are then released back into the greenhouse.
Two days later, she catches a sample of 120 ladybirds.
Amara finds that 20 of these ladybirds have paint on their shells.
Work out an estimate for the number of ladybirds in the greenhouse.
Write down an assumption you have made.
87 exam-style questions on WJEC GCSE Maths Capture Recapture. Each one has a worked solution and a mark scheme showing where the marks go.