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What is the expected value and variance for a Poisson distribution with parameter \(\mu=4.0\) ?

Short Answer

Expert verified
Expected value is 4.0 and variance is 4.0.

Step by step solution

01

Understand the Poisson Distribution

The Poisson distribution is a probability distribution that expresses the probability of a given number of events occurring in a fixed interval of time or space. It is characterized by the parameter \(\mu\), which represents the average number of events.
02

Recall the Expected Value of a Poisson Distribution

For a Poisson distribution with parameter \(\mu\), the expected value (mean) is equal to \(\mu\).
03

Compute the Expected Value

Given \(\mu = 4.0\), the expected value is \(E[X] = \mu = 4.0\).
04

Recall the Variance of a Poisson Distribution

For a Poisson distribution, the variance \(Var(X)\) is also equal to the parameter \(\mu\).
05

Compute the Variance

With \(\mu = 4.0\), the variance is \(Var(X) = 4.0\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Expected Value in Poisson Distribution
The expected value, also known as the mean, is a fundamental concept in probability and statistics. In the context of the Poisson distribution, which deals with the probability of a certain number of events occurring in a fixed period, the expected value is simply the parameter \( \mu \). This parameter represents the average number of occurrences in the given time or space interval.
  • If you imagine an event happening repeatedly, the expected value tells you the average number of times this event will occur.
  • For our example, when \( \mu = 4.0 \), it means on average, 4 events are expected to occur per interval.
Variance in Poisson Distribution
Variance is a measure of how spread out the numbers in your data set are around the mean. In simpler terms, it provides a sense of the data's consistency. For the Poisson distribution, an interesting fact is that the variance is equal to the expected value. This means the variance is also \( \mu \).
  • This characteristic highlights that in a Poisson distribution, the dispersion from the average number of events is as frequent as the average itself.
  • With \( \mu = 4.0 \), variance becomes \( Var(X) = 4.0 \), indicating some variability around the mean of 4 events, yet not wildly scattered.
Understanding Probability Distribution
A probability distribution defines how the values of a random variable (like the number of events) are distributed. The Poisson distribution specifically details how likely each number of events is, given \( \mu \).
  • It helps us to model and understand random events in real life. For instance, the number of customers arriving at a store within an hour could follow a Poisson distribution.
  • The distribution is often represented graphically, showing the probability of various outcomes. Peaks in the graph show the most likely outcomes.
Poisson distributions skew towards randomness, but the expected value and variance simplify predictions. By knowing both, we gain insight into what to expect and how much variability might occur.

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