5. There are two biscuit tins on a shelf. The red tin contains four chocolate biscuits and six plain biscuits. The blue tin contains one chocolate biscuit and nine plain biscuits. A child reaches into the red tin and randomly selects a biscuit. The child returns that biscuit to the tin, shakes the tin, and then selects another biscuit. a Draw a tree diagram that shows the possible outcomes. Place the appropriate probability on each branch of the tree diagram. b Find the probability that i both biscuits chosen are chocolate ii one of the biscuits is plain and the other biscuit is chocolate. c A second child chooses a biscuit from the blue tin. The child eats the biscuit and chooses another one from the blue tin. The tree diagram on the right represents the possible outcomes for this event. Write down the value of a and of b. Find the probability that both biscuits are chocolate. mi What is the probability that at least one of the biscuits is plain? d Suppose that, before the two children arrived, their brother randomly selected one of the biscuit tins and took out one biscuit. Calculate the probability that this biscuit was chocolate