Stats / Probability question

jaxson · Dec 18, 2006

I need to be brushed up on my probability formula. (been a while since I was in the classroom

I was having a discussion with a friend or mine last night. He was telling me how he was going to start tailing a few guys in college hoops that were hitting around 70%:lolBIG: . Anyway I did not want to challenge that, but we got in a fairly heated discussion on the following scenario:

"IF" the three guys are acheiving a 70% rate and picked one game each, what would be the percentage that all three would win on the same night? (my friend felt they would have the same 70% chance of sweeping the three plays)

Please someone correct me if I am wrong but wouldn't it be .70x.70x.70=.343 or 34% chance of them sweeping the board??

steaktartar · Dec 18, 2006

your friend isnt too bright not sure u are but u r right

StuntDouble1 · Dec 18, 2006

So if I bet a 3 -teamer (parlay) 10 days in a row. I will win 34% or roughly 3-4 days. Sounds high to me. Are you sure.??

jeckll · Dec 18, 2006

Actually you're both wrong. The fact that they're hitting 70% on the season has nothing to do with their future picks. You would be right if you could assum that there was a 70% chance of each one hitting their future picks, but you can't, so that's a totally arbitrary way to predict future picks.

Think of it this way...if a coin lands on Heads 4 out of 5 tries, do you think it has an 80% chance of hitting heads next?

steaktartar · Dec 18, 2006

the question was in theory if a guy is guaranteed to win at exactly 70 percent i am right of course it is not practical question but if the probability of an occurence is 7/10 and u have 3 picks that night....it is .7 times .7 times.7 of .343 or 34.3 percent chance all he asked was a simple math question

steaktartar · Dec 18, 2006

Stunt Double 1 said:
So if I bet a 3 -teamer (parlay) 10 days in a row. I will win 34% or roughly 3-4 days. Sounds high to me. Are you sure.??

another person misread question if u were guaranteed to pick70 percent winners everynight yes.......but u arent

jeckll · Dec 18, 2006

Well he didn't say that, but if that's the question, if you assume that they're going to hit 70% forever, then yeah...

jaxson · Dec 18, 2006

stunt,

the 34% was if they were hitting 70% AND were assumed to continue hitting 70%.

Theoretically a three team par would be hit 12.5% assuming each game was based on a 50/50 chance.