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Because not all airline passengers show up for their reserved seat, an airline sells 125 tickets for a flight that holds only 120 passengers. The probability that a passenger does not show up is \(0.10,\) and the passengers behave independently. (a) What is the probability that every passenger who shows up can take the flight? (b) What is the probability that the flight departs with empty seats?

Short Answer

Expert verified
(a) Calculate \(P(X \leq 120)\). (b) Calculate \(P(X < 120)\).

Step by step solution

01

Define the Random Variable

Let the random variable \( X \) represent the number of passengers who show up for the flight. We want to consider each passenger independently to determine if they show up, with probability \( p = 0.90 \) (since 0.10 is the probability of not showing up). Thus, \( X \) follows a binomial distribution \( \text{Binomial}(n, p) \) where \( n = 125 \) and \( p = 0.90 \).
02

Calculate the Probability for Question (a)

We need to determine the probability that every passenger who shows up can take the flight, which means at most 120 passengers show up out of 125. This can be calculated using the cumulative binomial probability: \[ P(X \leq 120) = \sum_{k=0}^{120} \binom{125}{k} (0.90)^k (0.10)^{125-k} \] This probability needs to be computed using a calculator or software with cumulative binomial functions.
03

Calculate the Probability for Question (b)

To find the probability that the flight departs with empty seats, we must determine the situation when fewer than 120 passengers arrive. This is represented by the probability \[ P(X < 120) = \sum_{k=0}^{119} \binom{125}{k} (0.90)^k (0.10)^{125-k} \] This also requires the use of a calculator or software that computes cumulative binomial probabilities.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Probability Theory
Probability theory is a branch of mathematics concerned with the analysis of random phenomena. It is the foundation for understanding and working with uncertainty and randomness, which is a pivotal part of many real-world settings.
In this particular exercise, probability theory helps us evaluate the likelihood of different scenarios when airline passengers show up for their flights. Here, we use concepts from probability theory to calculate probabilities for certain events, like the total number of passengers who show up being less than or equal to the plane's capacity.
In a scenario where each event (each passenger showing up) is independent, we can model these events using a binomial distribution. This forms a principal part of probability theory that deals with random events that have two possible outcomes, such as "show up" or "not show up".
Cumulative Probability
Cumulative probability is used to determine the probability that a random variable is less than or equal to a certain value. In simpler terms, it’s a way to find out the chance that something occurs up to a specific point.
In the airline problem, cumulative probability is applied by calculating the likelihood that up to 120 passengers show up, using the formula for cumulative distribution of a binomial random variable:
\[ P(X \leq 120) = \sum_{k=0}^{120} \binom{125}{k} (0.90)^k (0.10)^{125-k} \]
This formula sums up the probabilities of all possibilities from 0 passengers up to 120 passengers showing up. It gives us the overall chance that not more than 120 passengers will arrive.
Understanding cumulative probability is crucial for evaluating risks and outcomes in business, science, and daily life scenarios.
Random Variables
Random variables are essential concepts in probability theory. They are variables whose values depend on the outcomes of a random phenomenon. In simple terms, they are used to quantify random processes and are usually denoted by symbols, such as \( X \).
In the context of this exercise, \( X \) represents the number of passengers who show up for the flight. The value of \( X \) can vary depending on how many passengers decide to show up. Here, \( X \) follows a binomial distribution because it counts the number of successes (passengers showing up) in a fixed number of trials (tickets sold), each with the same probability of success (\( p = 0.90 \)).
Random variables like \( X \) enable us to model and make sense of uncertainties, allowing businesses and individuals to plan for different possible outcomes.

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Most popular questions from this chapter

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