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Author The handshake problem...
MikeLamb
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18th Jan 06 at 07:49   View User's Profile U2U Member Reply With Quote

50 people are in a room, they all shake hands, how many times are hands shaken???


Adam-D
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18th Jan 06 at 07:55   View User's Profile U2U Member Reply With Quote

2500
CCA
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18th Jan 06 at 07:55   View User's Profile U2U Member Reply With Quote

1225?
Jason Iles
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18th Jan 06 at 07:56   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by Adam-D
2500
Shane
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18th Jan 06 at 07:57   View User's Profile U2U Member Reply With Quote

none they have shaken there own hands
Jason Iles
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18th Jan 06 at 07:57   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by Jason Iles
quote:
Originally posted by Adam-D
2500



Bollox no it's not it's 2499 as they can't shake thier own hand?
CCA
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18th Jan 06 at 07:58   View User's Profile U2U Member Reply With Quote

jason it cant be 2499 as the other 49 people would still have to shake their own hand to get that number
Matt H
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18th Jan 06 at 08:02   View User's Profile U2U Member Reply With Quote

Do any of them have parkinsons?
Adam-D
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18th Jan 06 at 08:03   View User's Profile U2U Member Reply With Quote

in that case 2450
Pablo
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18th Jan 06 at 08:04   View User's Profile U2U Member Reply With Quote

2450
Jason Iles
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18th Jan 06 at 08:39   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by CCA
jason it cant be 2499 as the other 49 people would still have to shake their own hand to get that number


Dag nab it
Half Pint
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18th Jan 06 at 08:51   View User's Profile U2U Member Reply With Quote

hands are shaken once
Kathryn W
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18th Jan 06 at 09:25   View User's Profile U2U Member Reply With Quote

yup i'd say 2450
Tim
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18th Jan 06 at 09:26   View Garage View User's Profile U2U Member Reply With Quote

quote:
Originally posted by Adam-D
in that case 2450


But that would include repeated handshakes between the pairs. It's a maths combitionations question... 50-C-2 I think (and I don't have pascal's triangle to hand).
CCA
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18th Jan 06 at 09:28   View User's Profile U2U Member Reply With Quote

you need to use the equation n(n-1)/2 hence my answer
Rus
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18th Jan 06 at 09:33   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by CCA
you need to use the equation n(n-1)/2 hence my answer


why the n-1? just out of interest
Ojc
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18th Jan 06 at 09:34   View User's Profile U2U Member Reply With Quote

MATHS!OH MY GOD WTF ARE YOU TALKING ABOUT!
CCA
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18th Jan 06 at 09:39   View User's Profile U2U Member Reply With Quote

because if n is 50 then those 50 people cant shake 50 peoples hands as they would be shaking their own hand as well so its 50-1 the sum then becomes 50*49 divided by 2 giving the answer of 1225
Jamie Walby
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18th Jan 06 at 09:41   View User's Profile U2U Member Reply With Quote

What if there are people in the room with no arms
Jason Iles
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18th Jan 06 at 09:47   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by CCA
because if n is 50 then those 50 people cant shake 50 peoples hands as they would be shaking their own hand as well so its 50-1 the sum then becomes 50*49 divided by 2 giving the answer of 1225


You have no idea how turned on I am by this x x
Ally
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18th Jan 06 at 09:50   View User's Profile U2U Member Reply With Quote

quote:
Originally posted by Jamie Walby
What if there are people in the room with no arms


Of just one arm

Answer is once, hands are shaken once
Ally
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18th Jan 06 at 09:51   View User's Profile U2U Member Reply With Quote

There are five people in a room and each person shakes every other person's hand exactly one time. How many handshakes will there be?


FIND OUT We are asked to determine the total number of handshakes.
How many people are there? Five.
How many times does each person shake another's hand? Only once.
CHOOSE A STRATEGY Would it be possible to model this situation in some way? Yes, pick five friends and ask them to act out the problem. Should we do anything else? Keep track of the handshakes with a list.
SOLVE IT Get five friends to help with this problem.
Make a list with each person's name at the top of a column.
Have the first person shake everyone's hand. How many handshakes were there? Four.
Repeat this four more times with the rest of the friends. Write down who each person shook hands with. Our table should look something like this:

Rhonda Jagraj Rosario Kiran Margot

Jagraj Rosario Kiran Margot Rhonda
Rosario Kiran Margot Rhonda Jagraj
Kiran Margot Rhonda Jagraj Rosario
Margot Rhonda Jagraj Rosario Kiran


There were a total of twenty handshakes. But notice that each person actually shook everyone else's hand twice. (For example, Rhonda shook Jagraj's hand, and Jagraj shook Rhonda's hand.) Divide the total number of handshakes by two to find out the total number if each person had shaken every other person's hand only once. There were ten handshakes.


Half Pint
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18th Jan 06 at 09:55   View User's Profile U2U Member Reply With Quote

I got it right

it all about common sense and thinking outside the box
Ally
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18th Jan 06 at 09:55   View User's Profile U2U Member Reply With Quote

100
Tim
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18th Jan 06 at 10:06   View Garage View User's Profile U2U Member Reply With Quote

quote:
Originally posted by CCA
you need to use the equation n(n-1)/2 hence my answer


Or the full combinations equation...

n! / ( k! (n-k)! )

[Edited on 18-01-2006 by Tim]

 
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