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| Question 622122:  Determine whether each of the distributions given below represents a probability distribution.    Justify your answer.
 
 (A)
 x
 1
 2
 3
 4
 
 P(x)
 1/4
 1/12
 1/3
 1/6
 
 
 
 (B)
 x
 3
 6
 8
 
 P(x)
 0.2
 2/5
 0.3
 
 
 
 (C)
 x
 20
 30
 40
 50
 
 P(x)
 3/10
 -0.1
 0.5
 0.3
 
 
 
 
 Found 3 solutions by  solver91311, vleith, ewatrrr:
 Answer by solver91311(24713)
      (Show Source): 
You can put this solution on YOUR website! 
 A set of data is a probability distribution if and only if all of the data elements are positive and the sum of all the data elements is 1.
 
 John
 
  My calculator said it, I believe it, that settles it
 
 
Answer by vleith(2983)
      (Show Source): 
You can put this solution on YOUR website! I will say the first two are and the last one is not. The first two have a list of values, where the probabilities are all between 0 and 1 with a total of all listed of 1 or less. For those first two, assuming there are other values of x which are NOT shown, the listed values are between 0 and 1 AND their total is less than 1.
 The third one has a probability entry (the secocd one) less than 0. The total is 1, but you can't have a probability less than 0.
Answer by ewatrrr(24785)
      (Show Source): 
You can put this solution on YOUR website!  Hi,
 a. Yes, probabilities total to 1
 b. No, probabilities do not total to 1  (9/10)
 c. No, Probabilites  must be 0 ≤ p(x)≤ 1  P(x=30) = -.1 , not allowed
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