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A probability tree shows the possible routes through a sequence of events. In conditional probability, the second probability can depend on what happened first, so the branches after the first split may be different.
Conditional probability is written P(B∣A)P(B \mid A)P(B∣A), which means "the probability of BBB given that AAA has already happened". On any split in a tree, the branch probabilities must add to 1.
Without replacement means the first item is not put back before the second choice. That changes the total number left and may also change how many of each type are available.
Question 1
6 marksThere are only red marbles and green marbles in a bag. There are 6 red marbles and 4 green marbles.
Mason takes at random a marble from the bag. He does not put the marble back in the bag.
Mason takes at random a second marble from the bag.
In a probability tree diagram, all branches originating from the same point must sum to [ ].
Revision notes for Edexcel GCSE Maths Conditional Probability. Open the guide for explanations and worked examples. Written against the Edexcel GCSE Maths (1MA1) specification, so the content matches what's examinable rather than general Maths background.
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Given that a bus is late, the probability that Mia misses registration is 0.350.350.35. What is the probability that she does not miss registration, given that the bus is late?
