Bhavna has a bag containing a large number of beads.
She wants to find an estimate for the number of beads in the second sample that have been marked with a black cross.
Bhavna takes a sample of 30 beads from the bag.
She marks each bead with a black cross.
She then puts the beads back in the bag.
Bhavna shakes the bag.
She now takes another sample of 30 beads from the bag.
There are 180 beads in the bag.
Work out an estimate for the number of beads in the second sample that have been marked with a black cross.
Write down any assumptions you have made.
87 exam-style questions on Eduqas GCSE Maths Capture Recapture. Each one has a worked solution and a mark scheme showing where the marks go.