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Help with discrete random variables

  • Thread starter sneaky666
  • Start date
  • #1
66
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Homework Statement



1.
Suppose u flip a coin
Z = 1 if the coin is heads
Z = 3 if the coin is tails
W = Z^2 + Z
a)
what is the probability function of Z?
b)
what is the probability function of W?




2.
Let Z ~ Geometric (theta). Compute P(5<=Z<=9).

Homework Equations





The Attempt at a Solution



1.
what i think
a)
Pz(Z) = 1 if head
3 if tail
0 otherwise
b)
Pw(W) = 2 if head
12 if tail
0 otherwise

I don't see how the probability part comes into this, where do i include the 1/2 chance part...


or maybe its:
a)
Pz(Z) = 1/2 if Z is 1 or 3
0 otherwise
b)
Pw(W) = 1/2 if W is 2 or 12
0 otherwise

2.
 

Answers and Replies

  • #2
vela
Staff Emeritus
Science Advisor
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Education Advisor
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One of the important things you need to do in math is be precise with your notation. Tell us what is PZ(z) supposed to represent? That's where some of your confusion lies.
 

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