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anonymous
 one year ago
An urn contains six red balls, five white balls, and four black balls. Four balls are drawn from the urn at random without replacement. For each red ball drawn, you win $10, and for each black ball drawn, you lose $15. Let X represent your net winnings.
Compute E(X), your expected net winnings.
anonymous
 one year ago
An urn contains six red balls, five white balls, and four black balls. Four balls are drawn from the urn at random without replacement. For each red ball drawn, you win $10, and for each black ball drawn, you lose $15. Let X represent your net winnings. Compute E(X), your expected net winnings.

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anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I'm not good at this :P

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I'll give you a medal :D

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I need help not medal lol

misty1212
 one year ago
Best ResponseYou've already chosen the best response.2i cannot think of a snappy way to do this, this is going to take like forever

misty1212
 one year ago
Best ResponseYou've already chosen the best response.2first you have to think of all the possible outcomes when you pick 4 balls

misty1212
 one year ago
Best ResponseYou've already chosen the best response.2then you have to compute the amount of money you win or lose for each case then you have to find the probability of each possible outcome then you have to multiply and add !

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0could you lead me through the problem step by step please.

misty1212
 one year ago
Best ResponseYou've already chosen the best response.2if i had like two hours i could lets at least begin

misty1212
 one year ago
Best ResponseYou've already chosen the best response.2one possibility is you get all red and therefore win $40 the probability you get all red is \[\frac{\binom{6}{4}}{\binom{4}{15}}\]

misty1212
 one year ago
Best ResponseYou've already chosen the best response.2ok that is not quite right, the probabilty is \[\frac{\binom{6}{4}}{\binom{15}{4}}\]

misty1212
 one year ago
Best ResponseYou've already chosen the best response.2that is \(\frac{1}{91}\) http://www.wolframalpha.com/input/?i=%286+choose+4%29%2F%2815+choose+4%29

misty1212
 one year ago
Best ResponseYou've already chosen the best response.2then you could have 3 red, one white, win $30 that probability is \[\frac{\binom{6}{3}\times \binom{5}{1}}{\binom{15}{4}}\]

misty1212
 one year ago
Best ResponseYou've already chosen the best response.2this is really just a start there are lots of other possibilities i can't think of a quick way to do this though

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so if i get this right this is how it goes. P(1 red)=6C1×9C315C4 P(2 red)=6C2×9C215C4 P(3 red)=6C3×9C115C4 P(4 red)=6C415C4 P(1 red) = 0.369; P(2 red) = 0.396; P(3 red) = 0.132; P(4 red) = 0.011.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0the problem gets tough here on out i don't know what to do from here

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0P(1 red)=6C1×9C3/15C4 P(2 red)=6C2×9C2/15C4 P(3 red)=6C3×9C1/15C4 P(4 red)=6C4/15C4 correct way

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@kropot need your help from this part

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i didn't understand anything from here on out \

kropot72
 one year ago
Best ResponseYou've already chosen the best response.1P(1 black) = 0.484; P(2 black) = 0.242; P(3 black) = 0.32; P(4 black) = 0.001 E(X) = 10(0.369 + 0.396 + 0.132 + 0.011)  15(0.484 + 0.242 + 0.032 + 0.001)

kropot72
 one year ago
Best ResponseYou've already chosen the best response.1E(X) = a loss of $2.41.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@kropot72 but we need to find the net winnings not loss

kropot72
 one year ago
Best ResponseYou've already chosen the best response.1Expected net winnings = $2.41.

kropot72
 one year ago
Best ResponseYou've already chosen the best response.1"Net winnings" means (expected gains)  (expected losses). In this case the expected losses outweigh the expected gains.
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