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Aug 31st, 2005, 06:55 PM
#1
Thread Starter
Hyperactive Member
Prob. question.
Ok, person A randomly gets a number from 1 to 100.
Person B randomly gets a number from 1 to 70.
What are the chances that Person A's number is > Person B's number?
30% of the time, A will win regardless of what B gets.
The rest is 50/50? So would it be 30 % + 45%? or 75% of the time A will win?
[Edit]: It can't be exactly 30%, it must be at least > 50%, I'm guessing its 75%
Last edited by capsulecorpjx; Sep 1st, 2005 at 12:03 PM.
"I like to run on treadmills, because at least I know I'm getting nowhere."
- Me
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Sep 1st, 2005, 03:56 AM
#2
Addicted Member
Re: Prob. question.
I can prove by simulation that P(Xa) > P(Xb) is approximately equal to 0,65 but need some more time to do it analytically or perhaps I leave it to some other colleague in this forum.
...este projecto dos Deuses que os homens teimam em arruinar...
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Sep 1st, 2005, 04:22 AM
#3
Addicted Member
Re: Prob. question.
Let me add two more results that might bring some light on the way to the analytical solution:
If 1 <= Xa <= 100 and 1 <= Xb <= 100, then P(Xa) > P(Xb) = 0,50
If 1 <= Xa <= 100 and 1 <= Xb <= 50, then P(Xa) > P(Xb) = 0,75
...este projecto dos Deuses que os homens teimam em arruinar...
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Sep 1st, 2005, 12:26 PM
#4
Re: Prob. question.
I don't know where you get the 45% from.
30% of the time, A wins outright. Of the remaining 70%, it is split 50-50 which is to say 35% each.
Hence you get 65% in favour of A, 35% to B. Actually, it is slightly less than this because there is also the probability that they get the same number. But close enough.
zaza
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Sep 1st, 2005, 12:37 PM
#5
Thread Starter
Hyperactive Member
Re: Prob. question.
 Originally Posted by zaza
I don't know where you get the 45% from.
30% of the time, A wins outright. Of the remaining 70%, it is split 50-50 which is to say 35% each.
Hence you get 65% in favour of A, 35% to B. Actually, it is slightly less than this because there is also the probability that they get the same number. But close enough.
zaza
Thx! Stupid mistakes. I always make them.
"I like to run on treadmills, because at least I know I'm getting nowhere."
- Me
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