4 A bag contains 5 red discs and 1 black disc. Tina takes two discs from the bag at random without replacement.
- The diagram shows part of a tree diagram to illustrate this situation.
\section*{First disc}
\includegraphics[max width=\textwidth, alt={}]{e23cb28b-49e5-436a-942d-e6320029c634-3_264_494_479_550}
Complete the tree diagram in your Answer Book showing all the probabilities.
\section*{Second disc} - Find the probability that exactly one of the two discs is red.
All the discs are replaced in the bag. Tony now takes three discs from the bag at random without replacement.
- Given that the first disc Tony takes is red, find the probability that the third disc Tony takes is also red.