New Posts For Thread: Probabilty questionhttps://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-questionOne for those with greater maths knowledge than me.What are the chances/percentage odds of a consecutive sequence of 4 heads (or tails) occuring in 100 coin tosses-a) Onceb) Twicec) Three timesd) Four timesTIAon the upside, I got the right answerhttps://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-question?post_id=419151442#419151442on the upside, I got the right answerTue, 24 Nov 2009 11:58:46 -0600Aye robot,The problem with your approach is that it ignores the fact that a partial success in an uncompleted nth attempt (3 out of 3 heads) partially contributes to the probability of the success of the n + 1th attempt. If I've got 3 in a row in myhttps://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-question?post_id=419151438#419151438Aye robot,The problem with your approach is that it ignores the fact that a partial success in an uncompleted nth attempt (3 out of 3 heads) partially contributes to the probability of the success of the n + 1th attempt. If I've got 3 in a row in myTue, 24 Nov 2009 11:58:27 -0600I type too slow.https://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-question?post_id=419151430#419151430I type too slow.Tue, 24 Nov 2009 11:56:44 -0600I think (and im on the edge of my maths here so dont shout too loud if i**k it up ) that it's easier to see if you take it to "chance of getting two heads in three attempts)You would assume you have two 25% shotsHowever as you prepare to flip the thihttps://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-question?post_id=419151426#419151426I think (and im on the edge of my maths here so dont shout too loud if i**k it up ) that it's easier to see if you take it to "chance of getting two heads in three attempts)You would assume you have two 25% shotsHowever as you prepare to flip the thiTue, 24 Nov 2009 11:56:10 -0600Try solving the problem for a total of 5 tosses... by hand and via your formula.O.k- I see the problem. Give me a minute though because I'm sure there's a clean solution to this.https://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-question?post_id=419151422#419151422Try solving the problem for a total of 5 tosses... by hand and via your formula.O.k- I see the problem. Give me a minute though because I'm sure there's a clean solution to this.Tue, 24 Nov 2009 11:56:10 -0600Tigertiger,That's pretty uncanny. I was going to suggest something very similar.By Aye Robot's logic, the probability of not getting 2 heads in a row in 3 tosses is:(1 - 0.25) ^ 2 = 0.5625whereas, of course, the true answer is 5/8.https://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-question?post_id=419151418#419151418Tigertiger,That's pretty uncanny. I was going to suggest something very similar.By Aye Robot's logic, the probability of not getting 2 heads in a row in 3 tosses is:(1 - 0.25) ^ 2 = 0.5625whereas, of course, the true answer is 5/8.Tue, 24 Nov 2009 11:54:28 -0600Try solving the problem for a total of 5 tosses... by hand and via your formula.https://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-question?post_id=419151414#419151414Try solving the problem for a total of 5 tosses... by hand and via your formula.Tue, 24 Nov 2009 11:44:19 -0600so you don't get 97 attempts at allOf course you do- each throw represents the beginning of a new attemt regardless of the prior esquence. Each attemt is therefore independent.https://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-question?post_id=419151410#419151410so you don't get 97 attempts at allOf course you do- each throw represents the beginning of a new attemt regardless of the prior esquence. Each attemt is therefore independent.Tue, 24 Nov 2009 11:41:05 -0600Looking at it another way: Each time you set out to throw a coin four times you have a 1/16 chance of throwing four heads and therefore a 15/16 chance that you won't throw four heads. In a sequence of 100 throws you start again 97 times- so the chanchttps://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-question?post_id=419151406#419151406Looking at it another way: Each time you set out to throw a coin four times you have a 1/16 chance of throwing four heads and therefore a 15/16 chance that you won't throw four heads. In a sequence of 100 throws you start again 97 times- so the chancTue, 24 Nov 2009 11:39:45 -0600each toss is independent, each set of 4 is not as they all overlapyou don't get 97 fresh attempts, far less in practicehttps://community.betfair.com/general_betting/go/thread/view/94082/23469310/probabilty-question?post_id=419151402#419151402each toss is independent, each set of 4 is not as they all overlapyou don't get 97 fresh attempts, far less in practiceTue, 24 Nov 2009 11:38:06 -0600