Dan
Premium Member
Registered: 22nd Apr 02
Location: Gorleston on Sea, Norfolk
User status: Offline
|
0.0000219369?? which is what as a fraction 
Adult GiftsClick here to vist us
|
Dan
Premium Member
Registered: 22nd Apr 02
Location: Gorleston on Sea, Norfolk
User status: Offline
|
2.19/100000 = 1.095/50000
roughly 1 in 50000
[Edited on 17-12-2007 by Dan]
Adult GiftsClick here to vist us
|
AdZ9
Member
Registered: 14th Apr 06
User status: Offline
|
does this have something to do with BJ dan? 
|
Dan
Premium Member
Registered: 22nd Apr 02
Location: Gorleston on Sea, Norfolk
User status: Offline
|
noooo
Adult GiftsClick here to vist us
|
Aerox-lad
Member
Registered: 2nd Nov 07
Location: Melksham, Wiltshire
User status: Offline
|
1 in 3 is right
|
drunkenfool
Member
Registered: 7th Feb 03
Location: Hereford Drives: Audi R8 V8
User status: Offline
|
quote:
Originally posted by Aerox-lad
1 in 3 is right
No its not :S You dont have a 1 in 3 chance of flipping heads 21 times in a row! You have a 1/3 chance of doing it on the 21st attempt, but not 21 times in a row
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
|
The probability of multiple events ALL being true is calculated by multiplying all individual probabilities.
1 in 3 chance of hitting it is 2 in 3 chance of not hitting it?
Not hitting it 21 times is 2/3 to the power of 21.
ie. 2/3 x 2/3 x 2/3 x 2/3 .. 21 times.
= 2^21 / 3^21
= 2097152 / 10460353203
= 0.000200486
So roughly 1 / 4990 ish but its not a whole number so you can't have 1 as the numerator and I can't find any factors without a bit of work and Excel will only do it to three significant figures on the denominator and rounds anyway. I would imagine there are some.
[Edited on 18-12-2007 by Ian]
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
|
Zeroes in rows 18 to 21 are because it rounds down. Note that the fractions are mostly rounded anyway.
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
|
Google have more DP
http://www.google.co.uk/search?q=%282%2F3%29%5E21
|
jim_r1
Member
Registered: 6th Jun 07
Location: Nantwich, Cheshire
User status: Offline
|
quote:
Originally posted by Ian
The probability of multiple events ALL being true is calculated by multiplying all individual probabilities.
1 in 3 chance of hitting it is 2 in 3 chance of not hitting it?
Not hitting it 21 times is 2/3 to the power of 21.
ie. 2/3 x 2/3 x 2/3 x 2/3 .. 21 times.
= 2^21 / 3^21
= 2097152 / 10460353203
= 0.000200486
So roughly 1 / 4990 ish but its not a whole number so you can't have 1 as the numerator and I can't find any factors without a bit of work and Excel will only do it to three significant figures on the denominator and rounds anyway. I would imagine there are some.
[Edited on 18-12-2007 by Ian]
|
Dan
Premium Member
Registered: 22nd Apr 02
Location: Gorleston on Sea, Norfolk
User status: Offline
|
ian you are a mathmatical genious  thanks for the infomation
even at 1/5000 chance, i was robbed!!
Adult GiftsClick here to vist us
|
TheCam
Member
Registered: 16th Mar 07
Location: Kirkcaldy
User status: Offline
|
Some of the maths going on in this thread is comical, what ian says is correct. it is odds of 1/3 but that only means that if there are 300 of whatever it is and there are 3 possible outcomes then you are likely to win 100. so on your 21 shot the probability of you winning is stil 1/3 but if you say before you start what are the odds of me losing the first 20 then getting it on the 21st shot, thats when the odds go into thousands to 1
|
Jay
Member
Registered: 26th Sep 04
Location: Liverpool
User status: Offline
|
quote:
Originally posted by deano87
1 in something odds is bullshit tbh.
Most scratchcards are 1 in 4.6 chance of winning. I know someone that bought 5 scratchcards, 5 is more than 4.6, yeah?
Well, they didn't even win £1 back.
When my parents had a newsagents, for my birthday they gave me a pack of scratchcards with 120 cards in it, so £120, only got a return of £80 so lost £40. The 1 in 4.6 means 1 in every 4.6 cards from the WHOLE BATCH of scratch cards will win, in the pack I got, I could of won on nearly every one of them, but I never. Some where like 6 wins in a row, then nothing for say 15 cards.
[Edited on 18-12-2007 by JayM]
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
|
1 winning card in 4.6 is a lot slimmer than 1 in 4.6 chance on every card!
120 cards at those odds means about 26 are winners? Thats 21.6% of the batch.
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
|
quote:
Originally posted by JayM
Some where like 6 wins in a row, then nothing for say 15 cards.
That doesn't affect the odds of the whole batch as the order of the cards isn't important.
|
Lawrah
Premium Member
Registered: 25th Dec 04
User status: Offline
|
O0O0 Ian, your fractions.decimals and percentages make me so wet...
|
Jay
Member
Registered: 26th Sep 04
Location: Liverpool
User status: Offline
|
quote:
Originally posted by Ian
quote:
Originally posted by JayM
Some where like 6 wins in a row, then nothing for say 15 cards.
That doesn't affect the odds of the whole batch as the order of the cards isn't important.
Thats what I was trying to point out, that just cause he bought 5 in a row, doesnt mean he was gaurenteed a win.
|
Jamescorsa97
Member
Registered: 19th Aug 04
Location: Middlesbrough Drives: Cliosport 182
User status: Offline
|
OMG some of these maths made me LOL!
|
Jay
Member
Registered: 26th Sep 04
Location: Liverpool
User status: Offline
|
quote:
Originally posted by Ian
1 winning card in 4.6 is a lot slimmer than 1 in 4.6 chance on every card!
120 cards at those odds means about 26 are winners? Thats 21.6% of the batch.
But there where more than 26 winning cards, I think there was 30ish, the highest card I got was one for £5, what I mean by the batch is the amount of packs of 120 cards sold. So the 1 in 4.6 is in the whole batch, not each pack of scratch cards.
[Edited on 18-12-2007 by JayM]
|
strick206
Member
Registered: 12th Apr 07
Location: Wigan Drives:Integra DC5
User status: Offline
|
at some of the maths in this thread
deano with the scratchcards was comical
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
|
Yeah 4.6 is averaged over a number of batches. If you got 30 then you were a bit lucky although obviously not enough to hit the proper prizes!
|
TheCam
Member
Registered: 16th Mar 07
Location: Kirkcaldy
User status: Offline
|
although you got 30ish the next batch may only have had 10 or 15 winning cards.
[Edited on 18-12-2007 by TheCam]
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
|
The next batch should technically have 22 to average to 26 over both batches but I would imagine the sample is substantially larger than two batches to prohibit card counting.
|
AdZ9
Member
Registered: 14th Apr 06
User status: Offline
|
Dan what was this about? 
|
