Ecologists are studying the distribution of three plant species EEE, FFF, and GGG within a nature reserve. The probability that a randomly selected quadrat contains species EEE is 0.30.30.3, and the probability it contains species GGG is 0.40.40.4. Observations show that the conditional probability of finding species FFF given that species EEE is present is 0.40.40.4, and the probability that a quadrat contains species EEE or species FFF (or both) is 0.680.680.68.
Species EEE and GGG are known to be mutually exclusive.
Find P(E∪G)\text{P}(E \cup G)P(E∪G).
Show that the probability of a quadrat containing species FFF, P(F)\text{P}(F)P(F), is 0.50.50.5.
Given also that the presence of species FFF and GGG in a quadrat are independent events,
draw a Venn diagram to represent the distribution of these species, indicating the probability associated with each region.
200 exam-style questions on OCR (MEI) A Level Maths 2.3 Probability, covering 2.3.1 Calculate the probability of an event, 2.3.2 Complementary events, 2.3.3 Expected frequency of an event, 2.3.4 Diagrams to calculate probabilities, 2.3.5 Mutually exclusive and independent events, 2.3.6 Add probabilities for mutually exclusive events, 2.3.7 Multiply probabilities for independent events, 2.3.8 Mutually exclusive and independent events (notation) (A-level only), 2.3.9 Venn diagrams for probabilities (A-level only), 2.3.10 Conditional probabilities (A-level only), and 2.3.11 Independence via conditional probability (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.