Data published on March 1st, 2023 by the Ministry of Ecological Transition on the registration of private vehicles in France in 2022 contain the following information:
- $22.86\%$ of vehicles were new vehicles;
- $8.08\%$ of new vehicles were rechargeable hybrids;
- $1.27\%$ of used vehicles (that is, those that are not new) were rechargeable hybrids.
Throughout the exercise, probabilities will be rounded to the ten-thousandth.
Part IIn this part, we consider a private vehicle registered in France in 2022. We denote:
- $N$ the event ``the vehicle is new'';
- $R$ the event ``the vehicle is a rechargeable hybrid'';
- $\bar{N}$ and $\bar{R}$ the complementary events of $N$ and $R$.
- Represent the situation with a probability tree.
- Calculate the probability that this vehicle is new and a rechargeable hybrid.
- Prove that the value rounded to the ten-thousandth of the probability that this vehicle is a rechargeable hybrid is 0.0283.
- Calculate the probability that this vehicle is new given that it is a rechargeable hybrid.
Part IIIn this part, we choose 500 private rechargeable hybrid vehicles registered in France in 2022. In what follows, we will assume that the probability that such a vehicle is new is equal to 0.65. We treat the choice of these 500 vehicles as a random draw with replacement. We call $X$ the random variable representing the number of new vehicles among the 500 vehicles chosen.
- We assume that the random variable $X$ follows a binomial distribution. Specify the values of its parameters.
- Determine the probability that exactly 325 of these vehicles are new.
- Determine the probability $p(X \geq 325)$ then interpret the result in the context of the exercise.
Part IIIWe now choose $n$ private rechargeable hybrid vehicles registered in France in 2022, where $n$ denotes a strictly positive natural number. We recall that the probability that such a vehicle is new is equal to 0.65. We treat the choice of these $n$ vehicles as a random draw with replacement.
- Give the expression as a function of $n$ of the probability $p_n$ that all these vehicles are used.
- We denote $q_n$ the probability that at least one of these vehicles is new. By solving an inequality, determine the smallest value of $n$ such that $q_n \geqslant 0.9999$.