Subjects probability

Binomial Mgf

Step-by-step solutions with LaTeX - clean, fast, and student-friendly.

Use the AI math solver

1. The problem is to find the moment generating function (MGF) of the binomial probability distribution. 2. The binomial distribution models the number of successes in $n$ independent Bernoulli trials, each with success probability $p$. 3. The probability mass function (PMF) of a binomial random variable $X$ is: $$P(X=k) = \binom{n}{k} p^k (1-p)^{n-k}$$ where $k = 0, 1, 2, \ldots, n$. 4. The moment generating function $M_X(t)$ is defined as: $$M_X(t) = E[e^{tX}] = \sum_{k=0}^n e^{tk} P(X=k)$$ 5. Substitute the PMF into the MGF: $$M_X(t) = \sum_{k=0}^n e^{tk} \binom{n}{k} p^k (1-p)^{n-k}$$ 6. Factor the sum recognizing it as a binomial expansion: $$M_X(t) = \sum_{k=0}^n \binom{n}{k} (p e^t)^k (1-p)^{n-k} = (p e^t + 1 - p)^n$$ 7. Therefore, the moment generating function of a binomial random variable $X$ with parameters $n$ and $p$ is: $$\boxed{M_X(t) = (1 - p + p e^t)^n}$$ This function can be used to find moments of the distribution by differentiating with respect to $t$ and evaluating at $t=0$.