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Another maths puzzle
Tim 45 - 24/2/04 at 08:54 PM

Have a go at this one you may be surprised:

A university wanted to build a new campus. It was to have a maximum of seven lifts. But to economise they would have them stopping at only six floors. The students must be able to go to their destination WITHOUT changing lifts.
What is the largest number of floors the building could have?

lets see what you get

PS for clarification

[Edited on 24/2/04 by Tim 45]


Carl.H - 24/2/04 at 09:10 PM

36 I think


Julian B - 24/2/04 at 09:13 PM

Im 2 mins behind you and worked it out to be 36 if you count the ground floors to be a stop.....

Of course it could be bollo*


Tim 45 - 24/2/04 at 09:14 PM

close but your way off


Carl.H - 24/2/04 at 09:20 PM

I assume that all floors need a stop, and if your changing lifts they must be both on the same floor


Tim 45 - 24/2/04 at 09:29 PM

Sorry bout that carl.....read through the puzzle again, i omitted a major point.

Sorry once again


rusty nuts - 24/2/04 at 09:34 PM

6? Rusty


Tim 45 - 24/2/04 at 09:36 PM

nope


rusty nuts - 24/2/04 at 09:36 PM

assuming the lift goes to all floors it's 6 unless stairs are involved, Rusty


flak monkey - 24/2/04 at 09:39 PM

I think it is 18

David


Tim 45 - 24/2/04 at 09:43 PM

try using excel it becomes obvious


Carl.H - 24/2/04 at 09:54 PM

7 got there in the end (maybe)


Julian B - 24/2/04 at 10:24 PM

Well you have changed the question half way through ....... Just for clarification my arse

Sorry but i spent minutes working the answer out

Is it 1345678976 ?


JoelP - 24/2/04 at 11:19 PM

11!

already deleted that once but i've got there twice now!

just to explain my reasoning, one lift does 1-6, then its (2+7-11),(3+7-11)(4+7-11)(5+7/11) and finally (6+7-11).

any floor can go to any floor then i think.

[Edited on 24/2/04 by JoelP]


craig1410 - 24/2/04 at 11:55 PM

Well I make it 35 floors (plus ground floor) on the assumption that "getting to their destination" means from ground to some other floor and not inter-floor movements. If inter-floor movements are involved then the answer is 5 floors (plus ground).

When do you put us out of our misery then? It'll better be soon or I'm going to go fetch one of my Mensa puzzle books and get my own back!

Cheers,
Craig.


JamJah - 25/2/04 at 09:08 PM

I made it 36. All of them must stop at the ground floor plus 5 others 7 lifts times 5 floors each is 35 plus GF. How about adding a multi storey car park under it?


JoelP - 25/2/04 at 09:51 PM

i think you have to be able to go from any floor to any floor, otherwise its too easy to work out and wouldnt be a puzzle!


craig1410 - 25/2/04 at 11:40 PM

My 35 dis-counts ground floor as you normally talk about a 35 floor building as one having 35 floors over and above ground floor.

As I said, by my reckoning if you need to go from any floor to any floor without changing then it can only have 5 floors (plus ground = 6) so there's not much point in having 7 lifts unless you need the capacity. Is this the "surprise"?

Come on we've waited long enough for the answer!

Cheers,
Craig.


Carl.H - 25/2/04 at 11:48 PM

i think this shows how to get to 7 floors from any of the 7 floors

lift
lift


The Shootist - 25/2/04 at 11:50 PM

31 Floors


JamJah - 25/2/04 at 11:56 PM

if the answer was 7 wouldnt it make more sense to have each lift dedicated to its own floor? that way you can cram as many people in as possible and all get out at once. this then prevents the poor sod having to try and get out. althought it would still have to stop everywhere so time is still the same. it was a good thought at the time.
Ps. what university do you work at tim. and how much money have we just saved you!


JoelP - 26/2/04 at 09:37 AM

quote:
Originally posted by JoelP
11!

...just to explain my reasoning, one lift does 1-6, then its (2+7-11),(3+7-11)(4+7-11)(5+7/11) and finally (6+7-11).

[Edited on 24/2/04 by JoelP]


does this not work?! thats 11 floors (10 plus ground) with any combination possible...


Carl.H - 26/2/04 at 06:46 PM

'without changing lifts'?

how do you go from ground floor to floor 11 in one go?


suparuss - 26/2/04 at 07:00 PM

quote:
Originally posted by Carl.H
'without changing lifts'?

how do you go from ground floor to floor 11 in one go?


cos it bypasses some floors, and goes to straight to the highers ones, so youd have to choose which lift to catch depending o nthe floor you want


JoelP - 26/2/04 at 07:23 PM

i actually seem to have missed out the specifications of the 7th lift, which would link 1,7,8,9,10 and 11. hence 1st floor to the 11th without changing lifts!

did anyone notice i only mentioned 6 lifts?!?

btw, i wouldnt guarantee there cant be more than 11, but i certainly cant think how it would work. so i stick...

[Edited on 26/2/04 by JoelP]


Carl.H - 26/2/04 at 07:28 PM

that looks better, think you've cracked it Joel


craig1410 - 26/2/04 at 07:51 PM

Yip, I'd have to agree with this strategy so well done Joel (unless Tim decides to throw in another little point which he forgot to mention...)

Craig.


CairB - 26/2/04 at 07:56 PM

14


JoelP - 27/2/04 at 08:28 PM

so any hint as to the answer tim? am i right?


Tim 45 - 23/3/04 at 09:23 PM

No but keep trying


JoelP - 23/3/04 at 09:25 PM

you think im gonna keep trying after all this time?!?!?! you must be mad...

what is the answer?

i cant see how any more floors are possible...


Tim 45 - 23/3/04 at 09:32 PM

quote:

i cant see how any more floors are possible...




o but there are. Can anyone else solve this problem???


JoelP - 23/3/04 at 09:51 PM

technically, you dont specify that stairs arent allowed, so the answer is infinate.


Tim 45 - 23/3/04 at 09:53 PM

Nah..no tricks...no stairs (they're lazy students!)


JoelP - 23/3/04 at 09:58 PM

so just to make sure we have it straight, every floor needs to be linked to every floor via one lift trip. Ground floor is reffered to as 1st floor. 7 lifts that can stop at 6 floors each, and you cant jump out half way thru, and no firemans poles.

anything else?


Tim 45 - 23/3/04 at 10:04 PM

Yes Joel that is the correct puzzle....there are no tricks.....but what is the answer???
And how are the lifts configured?