Question

based on data obtained from the national institute of dental research, it has been determined that 41% of 12-year-olds have never had a cavity, 35% of 13-year-olds have never had a cavity, and 28% of 14-year olds have never had a cavity. if a child is selected at random from a group of 30 junior high students comprising five 12 year olds, ten 13 year olds, and fifteen 14 year olds and this child does not have a cavity, what is the probability that this child is 14 years old?

Can someone help me figure out how to solve this please? :)

Answer 1

@RaphaelFilgueiras @nirmalnema

Answer 2

I got 0.27 is this correct? Not sure if I'm doing this right.

Answer 3

I'm getting half that, but not sure if I'm identifying the conditional probability and the joint probability correctly.