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According to a survey conducted by OnePoll, a marketing research company, \(10 \%\) of Americans have never traveled outside their home state. Assume this percentage is accurate. Suppose a random sample of 80 Americans is taken. a. Find the probability that more than 12 have never travelled outside their home state. b. Find the probability that at least 12 have never travelled outside their home state. c. Find the probability that at most 12 have never travelled outside their home state.

Short Answer

Expert verified
The detailed calculation involves using cumulative binomial probability distribution. The exact numerical probabilities are not provided here as they need computation. However, the methods to calculate the probabilities are as described in steps 2-4.

Step by step solution

01

Determining Variables

First, identify the variables that are necessary to solve the problem. Here, n (the number of trials or the sample size) is 80, k (the number of 'successes') will vary depending upon the question, and p (the probability of a 'success') is 0.10.
02

Calculating Probability for More than 12

Now, to calculate the probability that more than 12 have never travelled outside their home state, we can use the complementary rule since it's easier to calculate the probability of the complementary event (12 or fewer). The probability of getting more than 12 is 1 minus the probability of getting 12 or fewer. We calculate this probability using the cumulative binomial probability formula P(X > 12) = 1 - P(X ≤ 12).
03

Calculating Probability for At Least 12

The probability that at least 12 have never travelled outside their home state basically indicates the probability of having 12 or more people. This includes exactly 12, 13, 14, and so on up to 80. Mathematically, P(X ≥ 12) = 1 - P(X < 12) = 1 - P(X ≤ 11). Again, the formula for cumulative binomial probability is used here. Because it is easier to calculate the probability of the complementary event (fewer than 12), we use the complementary rule.
04

Calculating Probability for At Most 12

The probability that at most 12 have never travelled outside their home state means the probability of having 12 or less people. This includes exactly 0, 1, 2 and so on up to 12. Mathematically, P(X ≤ 12) is what we need to calculate. This probability can be directly calculated using the cumulative binomial probability formula.

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