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    I'm stuck on this question. I know you can say that large fish in a pond are geometrically distributed with p = 3/7 which in turn means E(2X) = 2E(X) = 2(1/(3/7)) = 14/3 = 4 2/3, but the answer says it's 5 1/3. I can't understand why - is it a mistake?

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    (Original post by r3l3ntl3ss)
    I'm stuck on this question. I know you can say that large fish in a pond are geometrically distributed with p = 3/7 which in turn means E(2X) = 2E(X) = 2(1/(3/7)) = 14/3 = 4 2/3, but the answer says it's 5 1/3. I can't understand why - is it a mistake?

    Thanks.
    If you catch a large fish, the probabilities for catching the second large fish are different. You now have two large and four small in the pond.
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    (Original post by Gregorius)
    If you catch a large fish, the probabilities for catching the second large fish are different. You now have two large and four small in the pond.
    ah yes I see. Even then, you get 7/3 + 6/3 = 13/3 = 4 1/3, not 5 1/3?
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    (Original post by r3l3ntl3ss)
    ah yes I see. Even then, you get 7/3 + 6/3 = 13/3 = 4 1/3, not 5 1/3?
    Two large fish are left, not three. 7/3 + 6/2 = 5 1/3
 
 
 
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