Carlos wants to find an estimate for the number of ants in a colony.
He catches 60 ants from the colony and marks each one with a dye.
He then returns the ants to the colony.
A week later, Carlos catches another 60 ants.
9 of these ants are marked with the dye.
Work out an estimate for the number of ants in the colony.
Give your answer as an exact number and 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.