A certain company's IT department has found that 15% of all visitors to the company website arrive there in error. (They are actually looking for another website.) A random sample of 8 visitors to the website is chosen. Find the probability that fewer than 3 of them arrive in error.Do not round your intermediate computations, and round your answer to three decimal places.
Question
A certain company's IT department has found that 15% of all visitors to the company website arrive there in error. (They are actually looking for another website.) A random sample of 8 visitors to the website is chosen. Find the probability that fewer than 3 of them arrive in error.Do not round your intermediate computations, and round your answer to three decimal places.
Solution
This is a binomial probability problem where you are trying to find the probability of a certain number of "successes" (in this case, visitors arriving at the website in error) in a certain number of trials (in this case, 8 visitors).
The formula for binomial probability is:
P(X=k) = C(n, k) * (p^k) * ((1-p)^(n-k))
where:
- P(X=k) is the probability of k successes,
- C(n, k) is the combination of n items taken k at a time,
- p is the probability of success on a single trial, and
- n is the number of trials.
In this case, p = 0.15 (the probability a visitor arrives at the website in error), n = 8 (the number of visitors), and we want to find the probability that fewer than 3 of them arrive in error, i.e., P(X<3).
P(X<3) = P(X=0) + P(X=1) + P(X=2)
We can calculate each of these probabilities using the binomial probability formula:
P(X=0) = C(8, 0) * (0.15^0) * ((1-0.15)^(8-0)) = 0.279 P(X=1) = C(8, 1) * (0.15^1) * ((1-0.15)^(8-1)) = 0.377 P(X=2) = C(8, 2) * (0.15^2) * ((1-0.15)^(8-2)) = 0.282
Adding these probabilities together gives:
P(X<3) = 0.279 + 0.377 + 0.282 = 0.938
So, the probability that fewer than 3 of the 8 visitors arrive at the website in error is approximately 0.938, or 93.8%.
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