According to a study, regular users of public transport represent $17\%$ of the French population. Among these regular users, $32\%$ are young people aged 18 to 24 years old.
A person is randomly interviewed and we note:
- $R$ the event: ``The person interviewed regularly uses public transport''.
- $J$ the event: ``The person interviewed is aged 18 to 24 years old''.
Part A: - Represent the situation using a probability tree, reporting the data from the problem statement.
- Calculate the probability $P(R \cap J)$.
- According to this same study, young people aged 18 to 24 represent $11\%$ of the French population. Show that the probability that the person interviewed is a young person aged 18 to 24 who does not regularly use public transport is 0.056 to $10^{-3}$ precision.
- Deduce the proportion of young people aged 18 to 24 among non-regular users of public transport.
Part B: During a census of the French population, a census taker randomly interviews 50 people in one day about their use of public transport. The French population is large enough to assimilate this census to sampling with replacement. Let $X$ be the random variable counting the number of people regularly using public transport among the 50 people interviewed.
- Determine, by justifying, the distribution of $X$ and specify its parameters.
- Calculate $P(X = 5)$ and interpret the result.
- The census taker indicates that there is more than a $95\%$ chance that, among the 50 people interviewed, fewer than 13 of them regularly use public transport. Is this statement true? Justify your answer.
- What is the average number of people regularly using public transport among the 50 people interviewed?