SA lottery - nobbled?

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classic33

Leg End Member
I was thinking along those lines too!

Maybe there are hundreds of them which have each run a thousand times or so? In that case you could be talking about low millions of draws. The chance of a particular draw once in all of that time would be reduced from billions-to-one to maybe tens-or-hundreds-of-thousands-to one?

Then you would have to look at the question "What IS an odd-looking draw?" There are clearly quite a lot of possibilities, which reduces the odds further...

Consecutive rising numbers separated by 1... 1-6, 2-7... 15-20. 15 sets.
Consecutive falling numbers separated by 1... 20-15, 19-14... 6-1. 15 sets.
Consecutive rising numbers separated by 2... 1-11, 2-12... 10-20. 10 sets.
Consecutive falling numbers separated by 2... 20-10, 19-9... 11-1. 10 sets.

And so on. I reckon you could come up with a hundred or so sets of numbers which people would find odd. Now we are perhaps talking of hundreds-or-thousands-to-one - still unlikely, but no longer astoundingly unlikely!
Odds of that sequence of numbers coming up/being drawn being given as 42,000,000 to 1.

https://news.sky.com/story/south-af...-draw-produces-numbers-5-6-7-8-and-9-12149669
 

Accy cyclist

Legendary Member
You’d hate it. Too far south, isn’t it?
True. I haven't been south of Bolton in nigh on 20 years!🧐
 
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ColinJ

ColinJ

Puzzle game procrastinator!
Odds of that sequence of numbers coming up/being drawn being given as 42,000,000 to 1.
Approximately... :whistle:

If my 47 year old recollection of how permutations and combinations work is correct then it is (50! x 20) / (45! x 5!) which is 1:42,375,200.

If the order of the first 5 balls were significant then it would be 120 times less likely, 1:5,085,024,000.

I'm sure that if I am wrong then @si_c or one of the other forum mathematicians will soon be along to correct me! :laugh:
 

classic33

Leg End Member
Odds of that sequence of numbers coming up/being drawn being given as 42,000,000 to 1.

https://news.sky.com/story/south-af...-draw-produces-numbers-5-6-7-8-and-9-12149669
Approximately... :whistle:

If my 47 year old recollection of how permutations and combinations work is correct then it is (50! x 20) / (45! x 5!) which is 1:42,375,200.

If the order of the first 5 balls were significant then it would be 120 times less likely, 1:5,085,024,000.

I'm sure that if I am wrong then @si_c or one of the other forum mathematicians will soon be along to correct me! :laugh:
They were only slightly out on the odds then?
 

si_c

Guru
Location
Wirral
Odds of that sequence of numbers coming up/being drawn being given as 42,000,000 to 1.

https://news.sky.com/story/south-af...-draw-produces-numbers-5-6-7-8-and-9-12149669
So about the same as the UK lottery then.

It's not that unsurprising really, unlikely but not unexpected if lottery games are played over a long enough time. What would be really curious would be if they came out in that order - the odds of that happening are much smaller, but definitely non-zero.
Edit: for the powerball, about 1 in 3billion.
 
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Accy cyclist

Legendary Member
So i take it there's more chance of Accrington Stanley winning the 'European Cup' three years in a row than winning the damned thing?🧐
 
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ColinJ

ColinJ

Puzzle game procrastinator!
I altered the 'European Cup' to European Cup. Thinking surely everyone knows it's now called the Champions League.:wacko:
I wouldn't have a clue! I watched England win the World Cup in 1966 but then went to a grammar school where football was banned and rugby was played instead. I lost interest in football after that (but didn't get interested in rugby!)...
 

si_c

Guru
Location
Wirral
Approximately... :whistle:

If my 47 year old recollection of how permutations and combinations work is correct then it is (50! x 20) / (45! x 5!) which is 1:42,375,200.

If the order of the first 5 balls were significant then it would be 120 times less likely, 1:5,085,024,000.

I'm sure that if I am wrong then @si_c or one of the other forum mathematicians will soon be along to correct me! :laugh:

In terms of lotteries the probability of a given set of numbers is a function of the number of balls and the selected number of balls.

So it's 1 in the total number of combinations, this is calculated as 59! / (6! * 53!) in the case of the UK lotto - or about 1 in 45million. For the SA powerball example you have an initial pick of 5 balls from 45, and one powerball from 20. To calculate this we would use the permutations instead - we want one very specific permutation of these balls, so we calculate the number of permutations ( 45! / 40! ) and multiply by the 20 possibilities of the powerball to get the estimate I mentioned above.
 
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