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.