In this video, I introduce you to drawing tree diagrams as a way of simplifying calculations when combining probabilities.

It is important that you see all three questions as they differ in style. I also introduce you to the notation of conditional probability.

1) A bag contains 5 red sweets and 3 blue sweets. Two sweets are drawn at random i) with replacement and ii) without replacement.
Draw a tree diagram to represent the probabilities in each case.

2) Susan has the option of taking one of three routes to work A, B or C.
The probability of taking route A is 35%, and B is 25%.
The probability of being late for work if she goes by route A is 10% and similarly by route B is 5% and route C is 2%.
Draw a tree diagram to illustrate the probabilities.

3) A normal six sided fair die is thrown until a six is scored and then no more throws are made. The process continues up to a maximum of three throws.
Draw a tree diagram to illustrate the probabilities.