Conditional probabilityAQA A-Level Maths: Mind map

Exam questions on Conditional probability

1. In a group of 120 students, 70 study Biology, 50 study Chemistry and 20 study both. Twenty students study neither subject. One student is chosen at random.
   Determine whether studying Biology and studying Chemistry are independent.2 marks
2. A bag contains 5 red counters and 3 blue counters. Two counters are taken at random, one after the other, without replacement.
   Given that the second counter is red, find the probability that the first counter was blue.2 marks
3. In a survey of 80 people, 45 own a bicycle, 30 own a car and 12 own both.
   Find the probability that a person chosen at random owns neither a bicycle nor a car. Given that they own at least one of the two, find the probability that they own a bicycle.3 marks