Can PMF and MGF Be Directly Summed for Poisson and Exponential Variables?

  • Context: MHB 
  • Thread starter Thread starter nacho-man
  • Start date Start date
Click For Summary
SUMMARY

The discussion centers on the summation of the Probability Mass Functions (PMFs) and Moment Generating Functions (MGFs) of Poisson and Exponential random variables. The PMF for a Poisson-distributed variable is defined as \( P \{ N = n \} = \frac{(\beta T)^{n}}{n!} e^{-\beta T} \), while its MGF is expressed as \( E \{ e^{N t} \} = e^{\beta T (e^t-1)} \). Participants express confusion regarding the clarity of the problem statement and whether the solution involves identifying a specific distribution, such as a gamma or geometric random variable. The conversation highlights the need for clearer problem definitions in mathematical discussions.

PREREQUISITES
  • Understanding of Poisson distribution and its PMF
  • Familiarity with Moment Generating Functions (MGFs)
  • Knowledge of Exponential random variables
  • Basic concepts of probability theory
NEXT STEPS
  • Study the properties and applications of the Poisson distribution
  • Learn about Moment Generating Functions and their significance in probability
  • Explore the relationship between Poisson and Exponential distributions
  • Investigate the characteristics of gamma and geometric random variables
USEFUL FOR

Mathematicians, statisticians, and students studying probability theory, particularly those interested in the properties of Poisson and Exponential distributions.

nacho-man
Messages
166
Reaction score
0
is part a) simply the sum of the PMFs of the poisson and exponential random variables we are given?

I can't quite make sense of this question. Where it says "identify a distribution..."
is it looking for us to say something like a gamma random variable or a geometric random variable etc?

thank you!
 

Attachments

  • ass q1.jpg
    ass q1.jpg
    15.9 KB · Views: 98
Physics news on Phys.org
nacho said:
is part a) simply the sum of the PMFs of the poisson and exponential random variables we are given?

I can't quite make sense of this question. Where it says "identify a distribution..."
is it looking for us to say something like a gamma random variable or a geometric random variable etc?

thank you!

The statement of the problem is not clear at 100 x 100, but what I undestand is the PMF and MGF of the number N of customers arriving in a time T. N is Poisson distributed so that the PMF is... $\displaystyle P \{ N = n \} = \frac{(\beta\ T)^{n}}{n!}\ e^{- \beta\ T}\ (1)$ ... and the MGF is... $\displaystyle E \{ e^{N\ t}\} = \sum_{n=0}^{\infty} P \{N = n\}\ e^{n\ t} = e^{\beta\ T\ (e^t-1)}\ (2)$

Kind regards

$\chi$ $\sigma$
 
chisigma, a million thank yous are not enough to express my gratitude for you.

someone make this man a mod, he is legendary.

i am also happy that you also thought the question wasn't clear, that gives me some confidence :)

Thanks again, this is enough to get me started on the rest !
 
nacho said:
... someone make this man a mod, he is legendary...

Thank for Your compliments!... regarding the 'moderation' I consider myself totally unable to cover the role of moderator because I think that, in a family of people with the ideal to promote the mathematical knowledge, the figure of moderator shouldn't be necessary. For that reason I prefer to remain 'site helper' and to continue to do my best possible to MHB...

Kind regards

$\chi$ $\sigma$
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 12 ·
Replies
12
Views
4K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
4
Views
4K
  • · Replies 3 ·
Replies
3
Views
7K