DNA profiling is an invaluable tool for the police. However, when it comes to probability, things aren't always as straightforward as they seem.
99% of people who have measles have spots. Ben has spots. Do you think he has measles?
I'd be very surprised if I had three children all with the same birthday, but I read in the paper that it happened to one family...
In 1% of cases, an HIV test gives a positive result for someone who is HIV negative. How likely is it that someone who tests positive has HIV?
The probability that a passenger books a flight and does not turn up is 0.05. For an aeroplane with 400 seats how many tickets can be sold so that only 2% of flights are over-booked?
