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According to a Wakefield Research survey of adult women, \(50 \%\) of the women said that they had tried five or more diets in their lifetime (USA TODAY, June 21, 2011). Suppose that this result is true for the current population of adult women. A random sample of 13 adult women is selected. Use the binomial probabilities table (Table 1 of Appendix C) or technology to find the probability that the number of women in this sample of 13 who had tried five or more diets in their lifetime is a. at most 7 \(\begin{array}{ll}\text { b. } 5 \text { to } 8 & \text { c. at least } 7\end{array}\)

Short Answer

Expert verified
To solve this problem, apply the binomial probability formula for each specific case: a) calculating the probability for 0 to 7 successes, b) calculating the probability for 5 to 8 successes, and c) calculating the probability for 7 to 13 successes. Exact numbers will depend on the computations of these probabilities.

Step by step solution

01

Probability of at most 7 success

To find the probability of at most 7 successes, we need to sum the probabilities of having 0, 1, 2,..., up to 7 successes.So, \(P(X \leq 7) = P(X=0) + P(X=1) + P(X=2) + ... + P(X=7)\)Each \(P(X=k)\) can be calculated using the binomial probability formula.Remember that the binomial coefficient \[C(n,k) = \frac{n!}{k!(n-k)!}\]where \(n = 13\) (total number of trials), \(p = 0.5\) (probability of success), and \(k\) varies from 0 to 7.
02

Probability of 5 to 8 successes

To find the probability of having between 5 and 8 successes, we sum the probabilities of having exactly 5, 6, 7 and 8 successes.So, \(P(5 \leq X \leq 8) = P(X=5) + P(X=6) + P(X=7) + P(X=8)\)As in Step 1, each \(P(X=k)\) can be calculated using the binomial probability formula.
03

Probability of at least 7 successes

To find the probability of having at least 7 successes, we sum the probabilities of having exactly 7, 8, 9, 10, 11, 12 and 13 successes.So, \(P(X \geq 7) = P(X=7) + P(X=8) ... + P(X=13)\)As in previous steps, each \(P(X=k)\) can be calculated using the binomial probability formula.

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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 common probability distribution in statistics, important for modeling situations where there are two possible outcomes. These outcomes are commonly referred to as "success" and "failure." When you're dealing with a binomial distribution, you're often asking questions like, "what's the chance that success will occur a certain number of times?" in a set number of trials.

Key characteristics of a binomial distribution involve:
  • N number of trials: In this context, the exercise examines 13 adult women.
  • Two possible outcomes, such as success (a woman trying five or more diets) and failure (not trying five or more diets).
  • Each trial is independent, meaning the outcome of one trial does not affect another.
  • The probability of success denoted as p. For this exercise, the probability is 50% or 0.5.
The binomial distribution formulates this scenario mathematically, allowing us to calculate the probability of obtaining exactly k successes in n trials using the formula:\[ P(X = k) = C(n, k) \cdot p^k \cdot (1-p)^{n-k} \]Where \(C(n, k)\) is the binomial coefficient. This distribution is essential for answering probability-related questions like those in the exercise.
Probability Theory
Probability theory is the branch of mathematics concerned with analyzing random phenomena. In this context, it provides the foundation for calculating the likelihood of different outcomes in a sample of events or trials.

Core principles of probability include:
  • The sum of probabilities for all possible outcomes equals 1.
  • Probability can range from 0 (impossible event) to 1 (certain event).
  • For multiple independent events, their joint probability is the product of their individual probabilities.
When applying probability theory to binomial distribution, you use it to determine the probabilities for discrete outcomes (like the number of surveyed women trying diets).
In solving the exercise, probability theory helps sum the specific outcomes to find the probability for ranges (e.g., at most 7, 5 to 8, and at least 7).
Through probability theory, we can dissect complex problems into simpler, manageable calculations.
Statistical Analysis
Statistical analysis involves making sense of collected data by employing mathematical tools and methods. It applies probability theory and distributions (like binomial) to understand and predict patterns in data sets.

In exercises like the one described, statistical analysis might include:
  • Identifying trends or averages within the data (e.g., average number of women who have tried multiple diets).
  • Calculating probabilities or likelihoods for various scenarios using the binomial probability formula.
  • Interpreting results to answer questions or make predictions.
Statistical analysis provides the framework for taking raw data (such as survey results) and refining it into actionable insights. When calculating probabilities of diet trials, it helps pinpoint precise answers to specific query parts - like calculating the probability that 7 or more women have tried five or more diets.

Ultimately, statistical analysis aids in decision-making by making abstract data interpretations tangible and meaningful.
Random Sampling
Random sampling is a method used in statistical data collection that ensures every individual in the total population has an equal chance of getting selected. This process is vital for achieving unbiased results in statistical analysis.

In the context of the exercise:
  • A random sample of 13 adult women is selected.
  • The randomness assures that the sample is representative of the larger population.
  • It reduces the risk of skewed data due to sampling bias.
This sampling method is essential for drawing sound conclusions about populations from sampled data. When executing statistical analyses, like determining the probability of diet attempts among women, random sampling ensures the predictions accurately reflect the population's behavior. Consequently, it's a cornerstone practice in probability theory and statistical analysis that bolsters the integrity of study findings.

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Most popular questions from this chapter

During the 2011 NFL regular season, kickers converted \(83.5 \%\) of the field goals attempted. Assume that this percentage is true for all kickers in the upcoming NFL season. What is the probability that a randomly selected kicker who will try 4 field goal attempts in a game will a. convert all 4 field goal attempts b. miss all 4 field goal attempts

In a group of 12 persons, 3 are left-handed. Suppose that 2 persons are randomly selected from this group. Let \(x\) denote the number of left-handed persons in this sample. Write the probability distribution of \(x\). You may draw a tree diagram and use it to write the probability distribution. (Hint: Note that the selections are made without replacement from a small population. Hence, the probabilities of outcomes do not remain constant for each selection.)

The binomial probability distribution is symmetric for \(p=.50\), skewed to the right for \(p<.50\), and skewed to the left for \(p>.50\). Illustrate each of these three cases by writing a probability distribution table and drawing a graph. Choose any values of \(n\) (equal to 4 or higher) and \(p\) and use the table of binomial probabilities (Table I of Appendix \(\mathrm{C}\) ) to write the probability distribution tables.

Let \(x\) be a Poisson random variable. Using the Poisson probabilities table, write the probability distribution of \(x\) for each of the following. Find the mean, variance, and standard deviation for each of these probability distributions. Draw a graph for each of these probability distributions. a. \(\lambda=.6\) b. \(\lambda=1.8\)

A professional basketball player makes \(85 \%\) of the free throws he tries. Assuming this percentage holds true for future attempts, use the binomial formula to find the probability that in the next eight tries, the number of free throws he will make is a. exactly 8 b. exactly 5

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