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Tree diagram guide

Try writing on a branch yourself:
Step 1 of 4
  • The bag holds 3 red marbles and 2 blue; two are drawn, without putting back.
  • A branch for each outcome; its probability is written on it.
  • 35\displaystyle \frac{3}{5}, 0.6 and 60% are all read.
  • Enter moves on to the next branch: red again, after a red is out.
  • Check marks a probability with a mistake.
  • It marks a point where the branches leaving it do not add up to 1.
  • After a red marble is out, 4 are left, 2 of them red.
  • A path’s probability is the product of the probabilities along it: 35⋅24=620\displaystyle {\frac{3}{5}\cdot\frac{2}{4}}={\frac{6}{20}}.
  • Check says when a path’s probability is not the product of what you wrote on its branches.
  • The event: both marbles are the same colour.
  • A tap on a path marks it.
  • The event’s probability is the sum of its paths’ probabilities.