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A Harris Interactive survey for InterContinental Hotels \& Resorts asked respondents, "When traveling internationally, do you generally venture out on your own to experience culture, or stick with your tour group and itineraries?" The survey found that \(23 \%\) of the respondents stick with their tour group (USA Today, January 21,2004 ). a. In a sample of six international travelers, what is the probability that two will stick with their tour group? b. In a sample of six international travelers, what is the probability that at least two will stick with their tour group? c. In a sample of 10 international travelers, what is the probability that none will stick with the tour group?

Short Answer

Expert verified
(a) 0.255, (b) 0.262, (c) 0.072.

Step by step solution

01

Identify the Relevant Distribution

Since each traveler independently chooses whether to stick with a tour group or go on their own, with a given probability of success, this is a binomial distribution problem.
02

Define the Parameters

For part (a) and (b), we have a sample size, \(n = 6\). The probability of a traveler sticking with a tour group, \(p = 0.23\). For part (c), we have a sample size, \(n = 10\).
03

Use the Binomial Probability Formula (Part a)

The probability that exactly two travelers out of six stick with their tour group is given by the formula:\[ P(X = k) = \binom{n}{k} p^k (1-p)^{n-k} \]For part (a), \(n = 6\), \(k = 2\), and \(p = 0.23\):\[ P(X = 2) = \binom{6}{2} (0.23)^2 (0.77)^4 \]
04

Calculate Part a

First, calculate the binomial coefficient \(\binom{6}{2} = 15\). Then plug the values into the formula:\[ P(X = 2) = 15 \times (0.23)^2 \times (0.77)^4 \approx 0.255 \]
05

Sum Probabilities for At Least (Part b)

Part (b) asks for the probability that at least two people stick with the tour group. Calculate \( P(X \geq 2) \) by finding:\[ P(X \geq 2) = 1 - (P(X = 0) + P(X = 1)) \]
06

Calculate Part b

Calculate individual probabilities:\[ P(X = 0) = \binom{6}{0} (0.23)^0 (0.77)^6 \approx 0.296 \]\[ P(X = 1) = \binom{6}{1} (0.23)^1 (0.77)^5 \approx 0.442 \]Sum them: \(P(X < 2) = 0.738\).Then, calculate \(P(X \geq 2) = 1 - 0.738 = 0.262\).
07

Use the Binomial Probability Formula (Part c)

For part (c), where none of the 10 travelers stick with the tour group, calculate \(P(X = 0)\):\[ P(X = 0) = \binom{10}{0} (0.23)^0 (0.77)^{10} \approx 0.072 \]
08

Conclusion

Summarize the important probabilities: (a) The probability that exactly two out of six stick with the group is approximately 0.255. (b) The probability that at least two of six stick with the group is approximately 0.262. (c) The probability that none of ten stick with the group is approximately 0.072.

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Key Concepts

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

Binomial Distribution
The binomial distribution is a probability distribution that models the number of successes in a fixed number of trials. Each trial has two possible outcomes: success or failure. In our example, a "success" is when a traveler decides to stick with their tour group. The parameters of a binomial distribution are:
  • \(n\): Number of trials (e.g., six travelers sampling for parts a and b, ten travelers for part c.)

  • \(p\): Probability of success on a single trial (e.g., probability of a traveler sticking with the tour group is 0.23.)

To calculate specific probabilities, we use the binomial probability formula:\[ P(X = k) = \binom{n}{k} p^k (1-p)^{n-k} \]Here, \(\binom{n}{k}\) represents the number of possible combinations or ways to choose \(k\) successes out of \(n\) trials. Let's apply this formula to part (a): We calculated the probability that exactly two travelers out of six will stick with the tour group, which is roughly 0.255. This result demonstrates how we quantify the likelihood of exact outcomes using binomial distributions.
Statistical Analysis
Statistical analysis involves using mathematics to understand and interpret data. In the context of this problem, we use binomial distribution to make sense of survey data about the behavior of international travelers.For example, in part (b) of our exercise, the goal is to find the probability that at least two travelers stick with their group. Instead of calculating each probability "manually," statistical analysis allows simplification by using complement probabilities. We computed:
  • \( P(X \geq 2) = 1 - P(X < 2) \)

This means calculating the probability of zero or one travelers (complement events) and then subtracting from the total probability (1).This approach reduces work and helps manage computations when dealing with multiple probabilities. Statistical analysis in surveys provides insights into patterns and predicts outcomes based on sample behavior, which is a powerful tool for businesses, like InterContinental Hotels & Resorts, to understand customer tendencies.
Sample Size
Sample size, denoted as \(n\), is an essential element in probability distributions like the binomial distribution. A sample size determines the number of observations or trials we are assessing.Take our problem, for example:
  • For parts (a) and (b), the sample size is 6, exploring the behavior of six travelers.

  • For part (c), the sample size increases to 10.

A larger sample size tends to produce more reliable estimates of probabilities because there's more data to support the outcomes. In probability distributions, changes in sample size affect the calculations and results significantly. For instance, with a larger sample size in part (c), even though the probability of each traveler sticking with the group remains at 23%, the likelihood of none sticking shifts based on the increase in trials. This highlights why strategic selection of sample size is crucial in statistical analysis, ensuring robust and meaningful conclusions are drawn from the data.

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Most popular questions from this chapter

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