Week 18 - Challenger ($100K) - Ramat Hasharon, Israel

helki · Futures qualifying

RE: Week 18 - Challenger ($100K) - Ramat Hasharon, Israel

steven · Tennis legend

Chris is on Stadium Court at 13.00 BST on Tuesday with Josh following two matches later. These Challengers in Ramat Hasharon tend to attract a reasonably good crowd, so that might help Chris.

The bookies give Chris a 27% chance of winning his match and Josh a 35% chance of winning his. Looking on the bright side, that means around a 50% chance that one of them will get through even though neither of them are the favourite for their match.

Vandenburg · Futures level

0.27 x 0.35 does not eqaul a 50% chance
whos logerithmic proberbility therom are you applying to this.

(27/100) +(35/100)/2

=31% chance of one going through.

steven · Tennis legend

You had me worried for a second (what with pick 'em and all, it's been a long week), but how can there be only a 31% chance of one of them going through when there's a higher (35%) chance of Josh going through?

The probability of them both going out is the probability of both their opponents winning, i.e.

(1 - 0.27) x (1 - 0.35) = 0.4745

... so the probability of (at least) one of them going through is 1-0.4745, just over 50%.

Josh · Challenger level

Probability of Chris winning and Josh losing - 0.27 x 0.65 = 0.176

Probability of Josh winning and Chris losing - 0.35 x 0.73 = 0.256

Probability of one winning and the other losing - 0.176 + 0.256 = 0.432

So about a 43% chance of one winning, which is close enough to 50%.

steven · Tennis legend

Yes, that's exactly right and consistent with my figures because the split is:

43.2% just one winning (your figure)
9.3% both winning
--------
52.5% my "just over 50%"
47.5% both losing (as in my calculation)
--------
100.0%

(apologies to anyone reading this and getting very bored!

)

Drew · May 5, 2009

Ta guys....no wonder we have a 'reputation'

seagull · Hall of fame

OMG I thought I was a tennis geek but you guys take it to a new level!

Count Zero · Tennis legend

steven · Tennis legend

LOL ... sorry about that - I wasn't going to take it that far, but I couldn't let Vandenburg get away with saying I was talking rubbish.

Vandenburg · Futures level

i meant that 31% for both progressing.

steven · Tennis legend

I probably shouldn't rise to the bait here, but how could it be 31% for both progressing when Chris alone has only a 27% chance of winning? confuse

The Hoose · Satellite level

Actually, Steven's in the wrong here.

You need to use the formula P = V x p1 x p2

where

p1 = Probability of first Brit winning.
p2 = Probability of second Brit winning
V = The Vandenburg Factor

(if your calculator doesn't have a Vandenburg button, hit the PI key, multiply by 2 and deduct 3)

The Hoose · Satellite level

Back to business: Eaton serving at one game all.

The Hoose · Satellite level

Nice start from Eaton - yet to drop a point on serve, and he leads 2-1*