Practice Joint Probability Mass Function (pmf) (17.2.1)

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6 sample questions

Question 1.
Define a Joint Probability Mass Function.
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Think of it as a function relating two outcomes.
Question 2.
Give an example of a discrete random variable.
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Focus on countable outcomes.
3Question 3.
What does Joint PMF indicate?
- Probability of single events
- Joint likelihood of two events
- Marginal distribution
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Think about the combined outcomes.
4Question 4.
True or False: If two random variables are independent, their joint PMF can be expressed as the product of their individual PMFs.
- True
- False
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Recall the independence formula we discussed.
Question 5.
You are given a joint PMF where P(X=1, Y=1)=0.5, P(X=1, Y=2)=0.3, and P(X=2, Y=2)=0.2. Check if X and Y are independent.
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Sum the probabilities to find marginal values first.
Question 6.
You have P(X=1, Y=1)=0.25, P(X=1, Y=2)=0.25, P(X=2, Y=1)=0.25, P(X=2, Y=2)=0.25. Are X and Y independent?
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This illustrates proper checking for equality in independence.

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