Originally Posted by

**jacobaf20** I'm having trouble telling if this is meant to be conditional probability or not.

A chart showing results from a survey of adults regarding tattoos is shown below. Assuming the data are representative, estimate the probabilities that:

a) A randomly selected person has a tattoo, and

b) A randomly selected person of age between 18 and 29 has a tattoo.

Data:

At least one tattoo:

Age 18-29: 18

Age 30-50: 6

No tattoo:

Age 18-29: 32

Age 30-50: 44

For part a, I simply did the probability that someone would have a tattoo (any age). 18+6 = 24, or 24% probability that someone would have a tattoo. I think that's correct.

Part b is where I start to get a little confused. I thought I might need to use conditional probability, P(age 18-29 | at least one tattoo), which would be 18/24=75%. Then I started to question it, and wondered if it was maybe P(at least one tattoo | age 18-29), which would be 18/50=36%.

...now I'm wondering if the answer isn't just 18% (because 18 out of 100 people will be 18-29 and have one tattoo). I suppose that could be right, since the question never states "given that," which would signify conditional probability. Any help is greatly appreciated.