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Darla and Bill play a game where they pick 2 different numbers from the set {1, 2, 3, 4}. If the sum is larger than the product Darla wins. Otherwise Bill wins. What is the probability that Darla wins?

 Nov 20, 2014

Best Answer 

 #3
avatar+118687 
+5

Yes you are right mathematician  

 

Darla and Bill play a game where they pick 2 different numbers from the set {1, 2, 3, 4}. If the sum is larger than the product Darla wins. Otherwise Bill wins. What is the probability that Darla wins?

 

1,2      s=3    P=2      D

1,3      S=4    p=3     D

1,4      S=5    P=4      D

2,3       S=5   p=6       B

2,4       S=6   P=8         B

3,4       S=7    P=12      B

 

THE PROBABILTY THAT DARLA WILL WIN IS   1/2     OR     0.5     OR     50%

 Nov 21, 2014
 #1
avatar+23252 
+5

I'm going to assume that the choices are random choices, otherwise, Bill could always choose to win.

I'm also going to assume that the game is played "with replacement", meaning that both players choose from all four posibilities, not that one player gets two of the numbers, while the other player gets the two that are left. 

So, what are the possibilities for Darla?

1 + 2 = 3     1 + 3 = 4     1 + 4 = 5       2 + 3 = 5     2 + 4 = 6     3 + 4 = 7

There are 6 possibilities for Darla (we must count the two ways for Darla to get 5 as separate possibilities).

Now, what are the possibilities for Bill?

1 x 2 = 2     1 x 3 = 3     1 x 4 = 4     2 x 3 = 6     2 x 4 = 8     3 x 4 = 12

Each of the possibilities for Bill has a 1/6th chance of occuring.

In how many different ways can Darla beat Bill when

Bill gets 2?  6 ways  So Carla has a 6/6 chance to win.

Bill gets 3?  5 ways  So Carla has a 5/6 chance to win.

Bill gets 4? 4 ways  So Carla has a 4/6 chance to win.

Bill gets 6?  1 way  So Carla has a 1/6 chance to win.

Bill gets 8?  0 ways  So Carla has a 0/6 chance to win.

Bill ets 12?  0 ways  So Carla has a 0/6 chance to win.

So now we need to multiply the probability that Bill gets a certain result times the probability that Darla beats him and add all those results together:

(1/6)(6/6) + (1/6)(5/6) + (1/6)(4/6) + (1/6)(1/6) + (1/6)(0/6) + (1/6)(0/6)  =  16/36  =  4/9

The probability that Darla beats bill is  4/9.

If the choice is "without replacement" (one of them gets two of the numbers, the other gets the other two numbers) needs a different analysis. Re-post if that is the problem.

 Nov 20, 2014
 #2
avatar+1090 
0

Isn't the question asking the probability if only two numbers were picked? As in: Two numbers are picked in total, not two by each?

 Nov 20, 2014
 #3
avatar+118687 
+5
Best Answer

Yes you are right mathematician  

 

Darla and Bill play a game where they pick 2 different numbers from the set {1, 2, 3, 4}. If the sum is larger than the product Darla wins. Otherwise Bill wins. What is the probability that Darla wins?

 

1,2      s=3    P=2      D

1,3      S=4    p=3     D

1,4      S=5    P=4      D

2,3       S=5   p=6       B

2,4       S=6   P=8         B

3,4       S=7    P=12      B

 

THE PROBABILTY THAT DARLA WILL WIN IS   1/2     OR     0.5     OR     50%

Melody Nov 21, 2014

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