Edexcel S1 2021 June — Question 1

Exam BoardEdexcel
ModuleS1 (Statistics 1)
Year2021
SessionJune
TopicTree Diagrams
TypeSequential selection without replacement

  1. There are 7 red counters, 3 blue counters and 2 yellow counters in a bag. Gina selects a counter at random from the bag and keeps it. If the counter is yellow she does not select any more counters. If the counter is not yellow she randomly selects a second counter from the bag.
    1. Complete the tree diagram.
    First Counter
    Second Counter
    \includegraphics[max width=\textwidth, alt={}, center]{a439724e-b570-434d-bf75-de2b50915042-02_1147_1081_603_397} Given that Gina has selected a yellow counter,
  2. find the probability that she has 2 counters.