Question

In a forest, 20% of mushrooms are red, 50% brown, and 30% white. A red mushroom is poisonous with a probability of 20%. A mushroom that is not red is poisonous with a probability of 5%. What is the probability that a poisonous mushroom in the forest is red?
___ %

Answer 1

25% of red mushrooms will be poisonous

Answer 2

Draw a simple branch diagram to work the probabilities out. You find that the chance of a poisonous mushroom is 0.08 and the chance of a red poisonous is 0.04. So the probability that a poisonous mushroom is red is 1/2 or 0.5.