My Math Forum Help Un-Fry My Brain - Horse Probability

 Probability and Statistics Basic Probability and Statistics Math Forum

 June 4th, 2017, 12:35 PM #1 Newbie   Joined: Jun 2017 From: North Carolina Posts: 2 Thanks: 0 Help Un-Fry My Brain - Horse Probability Hi! Newbie here. I am trying to figure out a pretty basic natural probability question regarding a horse race and I would greatly appreciate anyone's help. So here goes: Imagine a horse race with 8 entries. Throw away all advantages and imagine that all 8 horses are equal. Now the natural probability of the #1 horse to come in in FIRST OR SECOND is .25, right? .125 chance for 1st .125 chance for 2nd What would be the natural probability for the #2 horse to then come in FIRST OR SECOND? Is it .125 or is it .1428? If we are going to say that the #1 horse WILL come in 1st or 2nd, then there are only 7 spots left. So, I'm thinking the correct answer is .1428. So the odds of the #1 horse coming in first or second AND the #2 horse coming in first or second should be .25 x .1428 = .0357 NOT .25 x .125 = .03125 Is this right? Thanks, in advance, for your input. Last edited by skipjack; June 5th, 2017 at 02:00 AM.
 June 5th, 2017, 06:18 AM #2 Senior Member   Joined: May 2016 From: USA Posts: 881 Thanks: 353 No, it is obviously wrong. If the horses are all alike, they have equal chances of coming in first or second. Probability that the second horse will come in second if first horse comes in first = $\dfrac{1}{7} * \dfrac{1}{8} = \dfrac{1}{56}.$ Probability that the second horse will come in first if first horse comes in second = $\dfrac{1}{7} * \dfrac{1}{8} = \dfrac{1}{56}.$ Probability that the second horse will come in first if the first horse does not come in first or second = $\dfrac{1}{7} * \dfrac{6}{8} = \dfrac{6}{56}.$ Probability that the second horse will come in second if the first horse does not come in first or second = $\dfrac{1}{7} * \dfrac{6}{8} = \dfrac{6}{56}.$ Probability that second horse will come in first or second $\dfrac{1}{56} + \dfrac{1}{56} + \dfrac{6}{56} + \dfrac{6}{56} = \dfrac{14}{56} = 0.25.$ Thanks from billnc Last edited by JeffM1; June 5th, 2017 at 06:20 AM.
 June 5th, 2017, 05:28 PM #3 Newbie   Joined: Jun 2017 From: North Carolina Posts: 2 Thanks: 0 So the probability that the #2 horse will come in first or second, IF the #1 horse comes is first or second, is 1 /56 + 1 / 56 which is 2/56 which is .0357142, which is where I had correctly landed, save a rounding error on my part. I wrote: "So the odds of the #1 horse coming in first or second AND the #2 horse coming in first or second should be .25 x .1428 = .0357" Thanks so much! Last edited by billnc; June 5th, 2017 at 05:41 PM.

 Tags brain, horse, probability, unfry

 Thread Tools Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post mickthetree Geometry 2 July 12th, 2014 11:01 AM Haley New Users 6 November 8th, 2012 06:55 AM Demo_Vers. Advanced Statistics 3 December 18th, 2009 05:22 PM M. Einstein Math Events 0 July 26th, 2009 10:14 AM Zomis Advanced Statistics 3 June 29th, 2007 09:03 AM

 Contact - Home - Forums - Cryptocurrency Forum - Top