A hotel located near a prehistoric tourism site offers two visits in the surrounding area, one to a museum and one to a cave.
A study showed that $70\%$ of the hotel's clients visit the museum. Furthermore, among clients visiting the museum, $60\%$ visit the cave. The study also shows that $6\%$ of the hotel's clients make no visits. We randomly question a hotel client and note:
- $M$ the event: ``the client visits the museum'';
- $G$ the event: ``the client visits the cave''.
We denote by $\bar { M }$ the complementary event of $M$, $\bar { G }$ the complementary event of $G$, and for any event $E$, we denote by $p ( E )$ the probability of $E$. Thus, according to the problem statement, we have: $p ( \bar { M } \cap \bar { G } ) = 0.06$.
- a. Verify that $p _ { \bar { M } } ( \bar { G } ) = 0.2$, where $p _ { \bar { M } } ( \bar { G } )$ denotes the probability that the questioned client does not visit the cave given that he does not visit the museum. b. The weighted tree opposite models the situation. Copy and complete this tree by indicating on each branch the associated probability. c. What is the probability of the event ``the client visits the cave and does not visit the museum''? d. Show that $p ( G ) = 0.66$.
- The hotel manager claims that among clients who visit the cave, more than half also visit the museum. Is this claim correct?
- The prices for visits are as follows:
- museum visit: 12 euros;
- cave visit: 5 euros.
We consider the random variable $T$ which models the amount spent by a hotel client for these visits. a. Give the probability distribution of $T$. Present the results in the form of a table. b. Calculate the mathematical expectation of $T$. c. For profitability reasons, the hotel manager estimates that the average amount of visit revenues must be greater than 700 euros per day. Determine the average number of clients per day needed to achieve this objective. - To increase revenues, the manager wishes the expectation of the random variable modeling the amount spent by a hotel client for these visits to increase to 15 euros, without changing the museum visit price which remains at 12 euros. What price should be set for the cave visit to achieve this objective? (We will assume that the increase in the cave entrance price does not change the frequency of visits to the two sites).
- We randomly choose 100 hotel clients, treating this choice as a draw with replacement. What is the probability that at least three-quarters of these clients visited the cave during their stay at the hotel? Give a value of the result to $10 ^ { - 3 }$ near.