Question

When u leave a party hall, you can do an alcohol test to check whether you are allowed to drive or not. However, the test is not 100% reliable: it only reacts positively on 94% of people who drink too much, and it also responds in 8% on people who do not drink too much. If you know that during this evening 40% of the attendees drank too much, calculate the probability that the test can reacts negatively, if this person has drunk too much. pls help me