Mathematics
Grade 12
15 min
Find probabilities using the binomial distribution
Find probabilities using the binomial distribution
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1
Introduction & Learning Objectives
Learning Objectives
Identify the four conditions of a binomial experiment.
Calculate the binomial coefficient C(n, k) and understand its role as a rational expression of factorials.
Apply the binomial probability formula to find the probability of exactly 'k' successes in 'n' trials.
Calculate cumulative probabilities, such as P(X ≤ k) or P(X ≥ k).
Determine the mean (expected value) and standard deviation of a binomial distribution.
Model and solve real-world problems using the binomial distribution.
Ever wondered about the probability of passing a 10-question multiple-choice quiz just by guessing? 🤔 The binomial distribution gives us the exact tool to find out!
In our study of rational functions, we've focused on expressions defined by ratios. We...
2
Key Concepts & Vocabulary
TermDefinitionExample
Bernoulli TrialA single random experiment with exactly two possible outcomes: 'success' or 'failure'. The probability of success is denoted by 'p', and the probability of failure is '1-p'.Flipping a single coin. 'Heads' can be a success (p=0.5), and 'Tails' a failure (1-p=0.5).
Binomial ExperimentAn experiment that consists of a fixed number of independent Bernoulli trials, where the probability of success remains constant for each trial.Flipping a coin 10 times and counting the number of heads. Here, n=10, and each flip is an independent Bernoulli trial.
Binomial Random Variable (X)A variable that counts the number of successes 'k' in a binomial experiment with 'n' trials.If we roll a st...
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Core Formulas
Binomial Probability Formula
P(X=k) = C(n, k) \cdot p^k \cdot (1-p)^{n-k}
Use this formula to find the probability of getting exactly 'k' successes in 'n' trials. Here, C(n, k) is the binomial coefficient, 'p' is the probability of success, and 'n' is the number of trials.
Binomial Coefficient Formula
C(n, k) = \binom{n}{k} = \frac{n!}{k!(n-k)!}
This is the formula for 'n choose k'. It calculates the number of combinations and acts as the coefficient in the binomial probability formula. Note its structure as a rational expression.
Mean (Expected Value) of a Binomial Distribution
\mu = E(X) = np
Calculates the average number of successes you would expect in a binomial experiment over the long run.
Standard Deviatio...
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Challenging
A vaccine has a 95% success rate. What is the minimum number of people that need to be vaccinated to be at least 99% sure that at least one person is successfully vaccinated?
A.2
B.3
C.4
D.5
Challenging
A binomial random variable X has a mean of 12 and a variance of 4.8. What are the values of n (number of trials) and p (probability of success)?
A.n = 30, p = 0.4
B.n = 24, p = 0.5
C.n = 20, p = 0.6
D.n = 15, p = 0.8
Challenging
You play a game where you roll a fair six-sided die 5 times. You win $10 for every '6' you roll, but lose $3 for every non-'6' you roll. What is the expected value of your net winnings from playing this game once?
A.-$4.17
B.$8.33
C.$12.50
D.-$2.50
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