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In a recent survey of women, \(90 \%\) admitted that they had never looked at a copy of Vogue magazine. Assuming that this is accurate information, what is the probability that a random sample of three women will show that fewer than two have read the magazine?

Short Answer

Expert verified
The final probability will be calculated by adding up the individual probabilities for the case where none and one woman has read Vogue. The detailed calculations will involve some computation using the binomial theorem.

Step by step solution

01

Calculation for no woman having read Vogue

The first event we will consider is the probability of none of the women having read Vogue. This can be calculated using the binomial probability formula, where n is the number of trials (3 in this case), k is the number of 'successes' (0), p is the probability of success (0.1, since it's given as women who have read Vogue), and q is the probability of failure (0.9, which corresponds to women who have not read Vogue). The formula is \( P(X=k) = \binom{n}{k} \times p^k \times q^{(n-k)} \)}. So, when no woman has read Vogue: \( P(X=0) = \binom{3}{0} \times (0.1)^0 \times (0.9)^3 \)
02

Calculation for one woman having read Vogue

The next event we will consider is the probability of one woman having read Vogue. This can be calculated similarly, with k=1: \( P(X=1) = \binom{3}{1} \times (0.1)^1 \times (0.9)^2 \)
03

Final Calculation

To find the overall probability that fewer than two women in the sample have read Vogue, we add together the probabilities calculated in the above two steps. i.e., \( P(X<2) = P(X=0) + P(X=1) \)

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Key Concepts

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

Binomial Distribution
In understanding the scenario of women reading a Vogue magazine, we are essentially dealing with a binomial distribution. A binomial distribution arises in situations where we perform a fixed number of independent 'trials' and each trial has only two possible outcomes: 'success' or 'failure'. In our case, each trial is a single woman's response, and a 'success' is when a woman has read Vogue, whereas a 'failure' is when she has not.

The key components of a binomial distribution include the number of trials (), the probability of success in a single trial (), and the total number of successes (). This distribution can tell us the probability of having exactly successes in trials, which is powerful because it gives us a way to predict the likelihood of an event over many trials. By using this framework, we can handle a wide variety of probability problems, such as determining the chance of a certain number of heads when flipping coins, or, as in our exercise, the likelihood that a given number of women have read a particular magazine.
Probability Calculation
Probability calculation is a fundamental aspect of statistics that helps us measure the chance of an event occurring. It is represented as a number between 0 and 1, where 0 indicates impossibility and 1 indicates certainty. To calculate the probability of an event in the context of a binomial distribution, we perform specific calculations for each possible number of successes.

For our survey question about women and Vogue magazine, we calculate the probability for each relevant event – no women having read the magazine and one woman having read it – individually. Each of these probabilities is a piece of the puzzle, and by adding them together, we can find the total probability of fewer than two women having read Vogue.

Understanding how to compute these probabilities allows students to tackle a wide range of problems, from genetics to marketing research, where predicting the likelihood of certain outcomes is essential.
Binomial Probability Formula
The binomial probability formula is the backbone of calculating probabilities in a binomial distribution. This formula, written as
\( P(X=k) = \binom{n}{k} \times p^k \times q^{(n-k)} \)

provides us with a way to calculate the probability () that an event will occur exactly () times (). In this formula, represents the number of trials, represents the number of desired successes, is the probability of success, and is the probability of failure (which can be calculated as 1 minus the probability of success). The binomial coefficient, \( \binom{n}{k} \)

, represents the number of ways to choose successes out of trials.

Looking at the exercise involving the survey of women and the Vogue magazine, we utilize the binomial probability formula to find the probabilities of zero and one woman having read the magazine. By computing these individually and adding them together, we get the overall chance of fewer than two women from a random sample having read the magazine. This practical application underlines the importance of the formula in solving real-world problems.

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