Deriving the PGF for Binomial Distribution using Combinations

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SUMMARY

The discussion centers on deriving the Probability Generating Function (PGF) for the Binomial Distribution using combinations. The participant has formulated the expression as \(\sum^{n}_{x=0}(nCx)(\frac{sp}{1-p})^x\) but seeks further simplification. Another contributor suggests correcting the expression to \(\sum_{x = 0}^n \binom{n}{x} (sp)^x (1 - p)^{n - x}\), emphasizing the importance of including the \((1 - p)\) terms. The derivation ultimately relies on the binomial theorem, which states that \((x + y)^n = \sum_{k = 0}^n \binom{n}{k} x^{n-k} y^k\).

PREREQUISITES
  • Understanding of Binomial Distribution
  • Familiarity with Probability Generating Functions (PGFs)
  • Knowledge of Combinatorial Notation (e.g., binomial coefficients)
  • Basic grasp of the Binomial Theorem
NEXT STEPS
  • Study the derivation of the Probability Generating Function for the Binomial Distribution
  • Explore the applications of the Binomial Theorem in probability theory
  • Learn about the implications of PGFs in statistical modeling
  • Investigate advanced combinatorial techniques for simplifying expressions
USEFUL FOR

Students in statistics, mathematicians focusing on probability theory, and anyone interested in the applications of the Binomial Distribution and its generating functions.

Darth Frodo
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Homework Statement



I'm trying to derive the PGF for the Binomial.


The Attempt at a Solution



I have it whittled down to \sum^{n}_{x=0}(nCx)(\frac{sp}{1-p})^x

I just don't know how to simplify this further. Any help is most appreciated.
 
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I think you lost some ##(1 - p)##s there, are you sure you didn't mean ##\sum_{x = 0}^n \binom{n}{x} (sp)^x (1 - p)^{n - x}##?

The result should follow from the binomial theorem,
$$ (x + y )^n = \sum_{k = 0}^n \binom{n}{k} x^{n-k} y^k. $$
 

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