Chapter 12: Problem 38
CHALLENGE Find the probability of exactly \(m\) successes in \(n\) trials of a binomial experiment where the probability of success in a given trial is \(p .\)
Short Answer
Expert verified
The probability of exactly \( m \) successes in \( n \) trials is given by \( P(X = m) = \binom{n}{m} p^m (1-p)^{n-m} \).
Step by step solution
01
Identify the Problem Type
This problem is a typical application of the binomial probability formula. We are trying to find the probability of getting exactly \( m \) successes in \( n \) trials.
02
Use the Binomial Probability Formula
The formula to find the probability of exactly \( m \) successes in \( n \) trials is given by:\[P(X = m) = \binom{n}{m} p^m (1-p)^{n-m}\] where \( \binom{n}{m} \) is the binomial coefficient, which can be calculated by \( \frac{n!}{m!(n-m)!} \).
03
Calculate the Binomial Coefficient
Calculate the binomial coefficient \( \binom{n}{m} \) using the formula:\[\binom{n}{m} = \frac{n!}{m!(n-m)!}\] This gives the number of ways to choose \( m \) successes out of \( n \) trials.
04
Calculate the Success Probability Component
Compute \( p^m \), which is the probability of having success in exactly \( m \) trials. This accounts for successful outcomes.
05
Calculate the Failure Probability Component
Compute \((1-p)^{n-m}\), which is the probability of having a failure in the remaining \( n-m \) trials.
06
Combine the Components
Multiply the results to form the complete probability for exactly \( m \) successes:\[P(X = m) = \binom{n}{m} p^m (1-p)^{n-m}\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Binomial Coefficient
In the context of binomial probability, the binomial coefficient plays a crucial role. It helps us determine the number of ways we can achieve exactly \( m \) successes in \( n \) trials. This is vital because, in a binomial experiment, the order of successes and failures matters, and the binomial coefficient lets us compute the possible arrangements efficiently.
The binomial coefficient is calculated using the formula:
The binomial coefficient is calculated using the formula:
- \( \binom{n}{m} = \frac{n!}{m!(n-m)!} \)
Probability of Success
The probability of success, denoted by \( p \), is another cornerstone of binomial probability problems. When we perform a binomial experiment, each trial has two possible outcomes: success or failure.
Here's what you need to know about the probability of success:
Here's what you need to know about the probability of success:
- It's the likelihood of a favorable outcome occurring in a single trial.
- If the probability of success is \( p \), then the probability of failure in any given trial is \( 1-p \).
Number of Trials
When dealing with binomial probability, one of the first steps is identifying the number of trials, denoted as \( n \). Each trial in a binomial experiment represents an individual occurrence of the process being studied.
Here's why the number of trials is important:
Here's why the number of trials is important:
- It sets the framework for how many times the event will be repeated.
- The number \( n \) influences both the number of possible outcomes and the structure of the binomial formula.
Factorial
Factorials are a fundamental concept used in calculating binomial coefficients. In mathematics, a factorial, represented by an exclamation mark (\(!\)), is the product of all positive integers up to a specified number, \( n \).
Consider these key aspects of factorials:
Consider these key aspects of factorials:
- For a positive integer \( n \), the factorial is given by \( n! = n \times (n-1) \times (n-2) \times ... \times 1 \).
- Factorials are utilized to calculate permutations and combinations, critical in binomial probability calculations.
- \( \binom{n}{m} = \frac{n!}{m!(n-m)!} \)