Ravina wants to find an estimate for the number of birds in a sanctuary.
She catches a sample of 84 birds in the sanctuary and tags each of these birds.
These birds are then released back into the sanctuary.
The next day she catches a sample of 55 birds in the sanctuary.
Ravina has tagged 11 of these birds.
Work out an estimate for the number of birds in the sanctuary.
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.