Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
A box has 3 red balls and 5 blue balls inside it. A ball is selected at random from the box and is not replaced. A yellow ball is then added to the box. A second ball is now selected at random from the box.
(i)[2]
Complete the tree diagram so that it shows every outcome and the probability on each branch.
(ii)[2]
Find the probability that the two balls chosen are the same colour.
(iii)[3]
Find the probability that the first ball chosen is red, given that the second ball chosen is blue.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme.