Till the lights go out

Kurt Godel · 13-02-2013 6:15pm

menoscemo wrote: »

You are assuming that the weighing scales are a balance, I think we are assuming they are an electronic type scale and not weighing one thing against another

My answer is
2. Weigh one set of coins. Weigh another. If one is heavier than the other it is the fake. If you get unlucky you require more weighings but it is possible to do it with 2 weighings if you are lucky.

This is akin to saying you just need one ticket to win the lottery, so the permutations of the numbers don't come into it. In any case, its not the correct answer.

BTH · 13-02-2013 6:17pm

I like Oryx answer. Requires some mental calculations too, but I like it

Kurt Godel · 13-02-2013 6:21pm

Discounted popular answer;

5 weighings. Call the stacks a,b,c,d,e,f,g,h,i,j.

1st weighing a,b,c
2nd weighing d,e,f
3rd weighing g,h,i

If all are equal you know that stack j must be counterfeit. However, if one of the weighings is greater than the other two (say a,b,c is heavier);

4th weighing a
5th weighing b
If one is heavier than the other, that's the counterfeit stack. If they are equal, c is the counterfeit.
Total 5 weighings.

But there is a way to do it with less.

menoscemo · 13-02-2013 6:21pm

Kurt Godel wrote: »

This is akin to saying you just need one ticket to win the lottery, so the permutations of the numbers don't come into it. In any case, its not the correct answer.

:mad:
But you said this:

Kurt Godel wrote: »

What is the smallest number of weighings needed to tell which stack is counterfeit?

Otherwise I think Oryx is right

Oryx · 13-02-2013 6:21pm

BTH wrote: »

I like Oryx answer. Requires some mental calculations too, but I like it

Prob not right tho.

mossym · 13-02-2013 6:22pm

BTH wrote: »

:rolleyes:

Right back at ya my friend.

i removed the sigh bit from my post as it was a bit ott. but my method was never doing any more weighs than i claimed to be doing, no matter how many times you claimed it was. hence the exasperation

Kurt Godel · 13-02-2013 6:24pm

Oryx wrote: »

4

1, 2:Weigh two sets of four, use lighter weight /4 to give weight of one stack
If both stacks equal weight the heavy stack is in neither
if one is heavier, 3 weigh two stacks from this (together), to decide where your heavy stack is.
Of the final two, 4 weigh one, and bobs your uncle.

Brilliant answer! Don't you love the sound of cogs turning?

Unfortunately, while correct, it can be done (with certainty!) with less weighings;)

mossym · 13-02-2013 6:25pm

i reckon it can be done in

3, using similar method than i used before but plaving all on then taking half off to see which half is heavier. it does require maths to see what a normal one weighs

but i'm running out the door now and don't have time to write the answer, suggestion as to how in teh spoiler, but don;t have time to write it out..someone will have it by time i get back

BTH · 13-02-2013 6:26pm

Kurt Godel wrote: »

Brilliant answer! Don't you love the sound of cogs turning?

Unfortunately, while correct, it can be done (with certainty!) with less weighings;)

Do I know in advance what the weight of a stack should be??

Kurt Godel · 13-02-2013 6:29pm

menoscemo wrote: »

:mad:

Take your semantics and cram 'em:D
If I bet you €1,000 that I could beat Gebrselassie at the Berlin marathon, would you pay up when I showed you photos of me giving him a knuckle sandwich?;)

Kurt Godel · 13-02-2013 6:30pm

BTH wrote: »

Do I know in advance what the weight of a stack should be??

Nope, only that a counterfeit coin is a gram heavier than a true one.

Oryx · 13-02-2013 6:31pm

I just know the proper solution is going to make me go Doh!

menoscemo · 13-02-2013 6:34pm

Kurt Godel wrote: »

Take your semantics and cram 'em:D
If I bet you €1,000 that I could beat Gebrselassie at the Berlin marathon, would you pay up when I showed you photos of me giving him a knuckle sandwich?;)

I bet you €1k That I already did beat Gebreselaisse at the Berlin marathon.

He dropped out

BTH · 13-02-2013 6:35pm

menoscemo wrote: »

I bet you €1k That I already did beat Gebreselaisse at the Berlin marathon.
He dropped out

Does that mean CL and Digs beat you??

Kurt Godel · 13-02-2013 6:36pm

mossym wrote: »

i reckon it can be done in
3, using similar method than i used before but plaving all on then taking half off to see which half is heavier. it does require maths to see what a normal one weighs

but i'm running out the door now and don't have time to write the answer, suggestion as to how in teh spoiler, but don;t have time to write it out..someone will have it by time i get back

I think I get what you're saying... but essentially that's more than one weighing. Otherwise, I could take my kids to those coin-operated weighing scales in Pharmacies, deposit my coin, weigh myself, then get Child 1 to hop on Pop, weigh us both (Total-Pop=Child1), then have Child2 grap onto my ears and jump up... that's three weighings;)

In any case, its incorrect.

shotgunmcos · 13-02-2013 10:42pm

WTF has this tough girl log morphed into?! One time, at band camp....

mossym · 13-02-2013 11:30pm

Kurt Godel wrote: »

I think I get what you're saying... but essentially that's more than one weighing. Otherwise, I could take my kids to those coin-operated weighing scales in Pharmacies, deposit my coin, weigh myself, then get Child 1 to hop on Pop, weigh us both (Total-Pop=Child1), then have Child2 grap onto my ears and jump up... that's three weighings;)

In any case, its incorrect.

Yeah I was counting the weigh when I took 5 off as a second weight, but still thought I could do it in three, to get a definite answer I need 4 though. Back to the drawing board.

Good question. Surprised no one has googled yet

Oryx · 14-02-2013 11:10am

shotgunmcos wrote: »

WTF has this tough girl log morphed into?! One time, at band camp....

I know the correct answer is one. I know it and I know KG will come along all smug with a ten line calculation to prove it and I still wont understand it.

I also wish I knew where the tough girl was gone, though.

A short one today, go up late, I have no excuses to offer, I was tired. A sluggish 5k is all. My legs are feeling the lack of running, I guess, plus, holy cow they hurt from mondays kb session. This is what happens when you dont do it for a month... But I have turbo later anyway, which should shake me up a bit.

Kurt Godel · 14-02-2013 11:38am

Oryx wrote: »

I know the correct answer is one. I know it and I know KG will come along all smug with a ten line calculation to prove it and I still wont understand it.

Awww- I know you googled that, coz I changed the question slightly;) Anyway, kudos for being closest with your method, and apologies for the hijack, back to tough barbie training!

Since we don't know the weight of a true coin, the correct answer is two. As follows:

(For clarity I will label the stacks 1,2,3,...,9,10).

First weighing: Place all of the stacks on the scales (keeping note of each stack). This might be any number, but for simplicity say the total weight is 1,010grams. You know the counterfeit stack adds 10g, so 100 true coins would weigh 1,000g, and one true coin weighs 10g.

Second weighing: Next, place on the scale
one coin from stack#1, two from stack#2, 3 from stack#3, etc. up to
all ten from stack#j. Had there been no counterfeit coins, the scale
would read (1+2+3+4+5+6+7+8+9+10)x10 = 55 x 10 = 550 grams. If the
counterfeit coins are in stack#1, the weight will be 551 grams, since
only one coin from stack#1 is included and the counterfeit coin weighs
1 gram more than the genuine coin. If the counterfeit coins are in
stack#2, the weight will be 552, since two coins from stack#2 are
included. In general, the weight should be 550 + N grams and N will be
the number of the stack containing the counterfeit coins!:)

Oryx · 14-02-2013 11:41am

Yeah, I figured your method had to be two, but knowing you, youd come up with some devious way of still doing it with one. Challenge to you, mathematician: can that be done with your version of the puzzle?

Kurt Godel · 14-02-2013 11:52am

Oryx wrote: »

Yeah, I figured your method had to be two, but knowing you, youd come up with some devious way of still doing it with one. Challenge to you, mathematician: can that be done with your version of the puzzle?

Hats off to anyone who can do it in one! Without knowing the weight of a true coin, I don't think it can (you need to know the comparison weights between the true and counterfeit).

Oryx · 14-02-2013 11:18pm

No mathmatics tonight but plenty of numbers. I did a truncated version of a turbo set that mimics one lap of the wimbleball 70.3 course. It starts with a 9 minute 60 cad hill climb and continues in that vein for fifty minutes. Lots of ups, downs, cadence and effort changes. It was hard but really good. 60 minutes including warm up and cool down. The full set goes on for nearly two hours and I hope to get to it soon.

Oryx · 15-02-2013 11:07am

Swim this morning. Some days are diamonds, but this one was definitely a stone. I felt heavy, tired and sluggish. My legs were in knots from last nights turbo. And to make it worse, a club mate in the next lane kept stopping at the end and saying out loud what I was thinking: 'I should have stayed in bed' 'Today is not a good day' 'I shouldnt have come' STFU man, youre making me worse!

400 wu
6 x50 kick
500 drills w pull
400 lungbuster
400 fc focus on catch

2000m 60 mins. Really off pace, but glad I got a reasonable set done in spite of wanting to give up after the wu.

My sbr totals are way down on last year so far
Swim 38 vs 39.5
Bike 530 vs 740
Run 120 vs 200
but I guess that's understandable, for one, Im not on an IM plan and for another, its been a struggle so far this year. At least anything Ive done has been quality work, and this week is better, so hopefully I'll continue to improve and get back on track, cos a hilly 70.3 beckons!

Oryx · 15-02-2013 12:41pm

So far this year, I have entered:
Wimbleball HIM (mid June)
BOTE (mid July)
Vitruvian HIM (late August)

And on the 'possibly' list:
Athy Oly (early June)
Shadowman HIM (August)

I'm listing them for motivation, so on days like today I remind myself where I need to be.

Izoard · 15-02-2013 12:46pm

Oryx wrote: »

So far this year, I have entered:
Wimbleball HIM (mid June)
BOTE (mid July)
Vitruvian HIM (late August)

And on the 'possibly' list:
Athy Oly (early June)
Shadowman HIM (August)

I'm listing them for motivation, so on days like today I remind myself where I need to be.

Some tasty ones there - will be interested to see how the Shadowman event(s) work out.

Oryx · 15-02-2013 11:34pm

Easy peasy lemon squeezy turbo set tonight. I was introducing two friends to the joy of the static bike so it was more about them than me. Neither had computers or hrms or even cleats, just straps, so we did steady effort, spin ups and little sprint intervals. I was trying not to load their legs too much, and we did plenty of recovery. A grand little leg loosener.

Oryx · 16-02-2013 11:09am

Ran this morning. It was slow. 11k in an hour. But that did involve stopping once to chat and again to deal with a wardrobe malfunction. But still its disheartening to be so sluggish. I have to remind myself that this is a rebuilding exercise and that I've got to take the steps one at a time. As usual by the last quarter I had settled into a nice groove and had picked up the pace. It was better than Thursdays run at any rate.

Oryx · 16-02-2013 6:36pm

I got bullied into chatting to a doctor (husband of a friend) today, and I've got to admit, it was what I should have done ages ago (but I'm doctor phobic, what can I say?). Got to the cause of an allergic reaction Ive suffered with for the last two months in oh, two seconds flat. Im also getting full bloods done to see why Im so off form these days. My faith in the medical profession is still shaky, but I have a lot of time for this guy.

Oryx · 17-02-2013 4:38pm

Busy day today. Got out early for a gentle ten miler, but this got interrupted when I came upon the leftover flotsam from a house burglary strewn all over the road, clearly the thieves had no need for passports and bank books and had ditched them. Being a model citizen I collected it all up, tracked down the owner and got them back to him. It was all very exciting. Continued on my run, feeling all warm and fuzzy.

Went for a swim later where I was trying to encourage a reluctant hero into swimming, as part of coaching practice. Did about 1500 but this was very stop start, only got going once my coaching guinea pig had left.

Physically I feel so much better since my friends intervention yesterday. (They even gave me the medicine I need) so it was lovely that I got to do a bit of paying it forward on the good deeds front today.

Oryx · 19-02-2013 11:33am

Took an easy day yesterday. Well, I say easy, I did a mahoosive amount of domestic maintenance that's needed doing for a while. Me and the washing machine never stopped all day. My motivation has suddenly come back from the wilderness.

Got out to kettlebells last night, and enjoyed the set. Sometimes you just get into a calm headspace where you forget everything but the work. Even though you're working hard, its almost relaxing. Body felt strong and I managed it all, including a 2min 40 plank. I'm enjoying this renewed me.

I have fasting blood tests tomorrow. I even got a phone call to book the appointment, cos well, I might have just forgotten.... I wasn't let forget. I love my friends.

Till the lights go out

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