bac-s-maths 2024 Q1

bac-s-maths · France · bac-spe-maths__amerique-nord_j2 5 marks Binomial Distribution Contextual Probability Requiring Binomial Modeling Setup
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 I
In 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 $R$.

  1. Represent the situation with a probability tree.
  2. Calculate the probability that this vehicle is new and a rechargeable hybrid.
  3. Prove that the value rounded to the ten-thousandth of the probability that this vehicle is a rechargeable hybrid is 0.0283.
  4. Calculate the probability that this vehicle is new given that it is a rechargeable hybrid.

Part II
In 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.
  1. We assume that the random variable $X$ follows a binomial distribution. Specify the values of its parameters.
  2. Determine the probability that exactly 325 of these vehicles are new.
  3. Determine the probability $p(X \geq 325)$ then interpret the result in the context of the exercise.

Part III
We 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.
  1. Give the expression as a function of $n$ of the probability $p_n$ that all these vehicles are used.
  2. 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 $q_n \geqslant 0.9999$.
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:
\begin{itemize}
  \item $22.86\%$ of vehicles were new vehicles;
  \item $8.08\%$ of new vehicles were rechargeable hybrids;
  \item $1.27\%$ of used vehicles (that is, those that are not new) were rechargeable hybrids.
\end{itemize}

Throughout the exercise, probabilities will be rounded to the ten-thousandth.

\textbf{Part I}

In this part, we consider a private vehicle registered in France in 2022.\\
We denote:
\begin{itemize}
  \item $N$ the event ``the vehicle is new'';
  \item $R$ the event ``the vehicle is a rechargeable hybrid'';
  \item $\bar{N}$ and $\bar{R}$ the complementary events of $N$ and $R$.
\end{itemize}

\begin{enumerate}
  \item Represent the situation with a probability tree.
  \item Calculate the probability that this vehicle is new and a rechargeable hybrid.
  \item Prove that the value rounded to the ten-thousandth of the probability that this vehicle is a rechargeable hybrid is 0.0283.
  \item Calculate the probability that this vehicle is new given that it is a rechargeable hybrid.
\end{enumerate}

\textbf{Part II}

In 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.

\begin{enumerate}
  \item We assume that the random variable $X$ follows a binomial distribution. Specify the values of its parameters.
  \item Determine the probability that exactly 325 of these vehicles are new.
  \item Determine the probability $p(X \geq 325)$ then interpret the result in the context of the exercise.
\end{enumerate}

\textbf{Part III}

We 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.

\begin{enumerate}
  \item Give the expression as a function of $n$ of the probability $p_n$ that all these vehicles are used.
  \item 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 $q_n \geqslant 0.9999$.
\end{enumerate}
Paper Questions