Suppose a flu test has the following results: If a person is healthy, it returns negative 90% of the time If a person is healthy, it returns positive 10% of the time If a person is sick, it returns...

Suppose a flu test has the following results:

If a person is healthy, it returns negative 90% of the time
If a person is healthy, it returns positive 10% of the time
If a person is sick, it returns negative 1% of the time
If a person is sick, it returns positive 99% of the time

Suppose 4% of people actually have the flu. If a person tests positive for flu, what’s the probability they are actually sick?