A riddle

[Yo Ma Ma]

Originally posted by: chuckywang

Originally posted by: Yo Ma Ma

Start with 5 races. Each horse races in one of these.

obviously, the 4th and 5th place horses from each race are no longer in contention... 10 horses eliminated.

Isn't there a problem where the 2 slower horses say from race #1 could be faster than the entire set of 5 from a different race? So you can't just eliminate the 10 'slowest' without some kind of rematch, right?

No, the 2 slowest horses of any race cannot be in the top 3 since there are 3 horses faster than it.

/slaps hand to forehead - - oh yeah!

 

[scorpmatt]

A plate of cookies to the ones that figured it out before my head exploded.

 

[cKGunslinger]

Originally posted by: Yo Ma Ma

Start with 5 races. Each horse races in one of these.

obviously, the 4th and 5th place horses from each race are no longer in contention... 10 horses eliminated.

Isn't there a problem where the 2 slower horses say from race #1 could be faster than the entire set of 5 from a different race? So you can't just eliminate the 10 'slowest' without some kind of rematch, right?

I'll assume you've read the other replies. Obviously, if any horse has come in 4th or 5th, he has no shot at being in the top 3. If you wanted rankings all the way down to 25th place, then yeah, you'd need some rematches, but that's not the case here.

 

[Ready]

25 horses to start so you have 5 races.
Top three for each race advance now you're left with 15

5(1st place) 5(2nd place) 5(3rd place)

If one of the top 3 horses came in 3rd place, then the only possible way it came into 3rd place is if in the first series of race, all 3 top horses were in the same race, thus it's not possible for 2 top 3 horses to finish 3rd. So you race all the 3rd placers and advance the fastest. Now your left with

Thats 6 races so far

5(1st placer from first race) 5(2nd placers from 1st race) 1(first placer from the pool of 3rd places)

We are left with 11 horses. 3 more race and the top 3 should be good. So I say the total number of races shoiuld be 9. Maybe less but too lazy to think

 

[Ready]

Originally posted by: DrPizza
Another quick solution, if you're looking for a guarantee (edit: I think this actually is the minimum # of races possible, unless some weird if-then strategy yields 6 races)

Start with 5 races. Each horse races in one of these.

obviously, the 4th and 5th place horses from each race are no longer in contention... 10 horses eliminated.

Now for the playoffs.
Top horse from each race in the first playoff
(this is race 6)
whichever horses finish 4th and 5th in that race, you don't have to consider them or the other horses in their first races... you've eliminated a total of 6 more horses... the field has been narrowed to 9.

I don't get this one. How do you eliminate 6 horses from 1 race?

nvm..didn't read it carefully enough guess that would work

 

[Ready]

what if the fastest 3 horses were just having a bad day and lost?

 

[Furyline]

cool problem :thumbsup:

I was so close!

 

[Ready]

Let me see if i understand the solution
Begin
a(1,2,3,4,5) b(1,2,3,4,5) c(1,2,3,4,5) d(1,2,3,4,5) e(1,2,3,4,5)

after 5 races

we have
a(1,2,3) b(1,2,3) c(1,2,3) d(1,2,3) e(1,2,3)

Race6
race a(1) b(1) c(1) d(1) e(1)

suppose the winners where in order a(1) b(1) c(1) then we can eliminate all of d and e
leaving only
a(1,2,3) b(1,2,3) c(1,2,3)

since c(1) is at best 3rd, then everything else in c is eliminated leaving

a(1,2,3) b(1,2,3) c(1)

since b(1) is at best 2nd and b(2) is at best 3rd the rest of b is also eliminated leaving
a(1,2,3) b(1,2) c(1)

since we know a(1) is the fastest then a(2,3) b(1,2) and c(1) race for 2nd and 3rd in the final 7th race

 

[Chode Messiah]

shoot all the horses and buy a car

 

[HomeBrewerDude]

see Dr. Pizza's post.

 

[NiKeFiDO]

i woudl be really really pissed if this happened to me @ a job interview.

 

[MAME]

Originally posted by: NiKeFiDO
i woudl be really really pissed if this happened to me @ a job interview.

how DARE they ask you a question that involves problem solving skills