In a botanical survey of a large woodland area, trees are classified as being either Deciduous or Evergreen.
Of the Deciduous trees, 90% are found to be carrying a specific fungal infection. Of the Evergreen trees, 25% are found to be carrying the same infection.
The proportion of trees in the woodland that are Deciduous is kkk.
Draw a tree diagram to represent this information.
In the survey, 70.5% of all trees were found to be carrying the infection.
Find the value of kkk.
One tree is selected at random from the woodland. Given that this tree is infected, find the probability that it is a Deciduous tree.
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.