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Weekend Brain Drill: Can You Solve This In 30 secs? - Education (6) - Nairaland

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Re: Weekend Brain Drill: Can You Solve This In 30 secs? by buske(m): 12:03am On Jul 20, 2015
There were five (5) people at the occasion. If everyone of them shook hands with themselves, you have 5!=120 handshakes
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by youngice(m): 12:05am On Jul 20, 2015
yorme:
The Answer is 5. Handshakes between 5 people will result in a total of 120 handshakes.

5! = 120 handshakes.
na only you get sense
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by obiscolly(m): 12:21am On Jul 20, 2015
lool..i know there are easier ways to go about it, but i just felt like putting my permutation and combination skills to good use. It's been a while.
So this is a combination problem. So let the number of people shaking hands be n, then we are solving for n where nC2 = 120.
This gives n!/(n-2)!2! = 120. Simplifying gives n(n-1)(n-2)!/(n-2)!2!=120, which further simplifies to n(n-1)/2=120, then n(n-1)=240. Opening the brackets and expressing in quadratic form n^2-n-240=0. Solving for n gives 16.

So we have 16 people shaking hands grin
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Nobody: 12:28am On Jul 20, 2015
This's realy puzzling!
Well i wont go 'still' unnotice without droping the litle my brain could produce (at least for tonight)
FIRSTLY MY ANSWER IS 12-GUESTS EVENT!
HOW? fine gud question!
But b4 anything, pls understand that I'm not mathmatician...I read Mass Comm!
NOW TO FORM THE FORMULAR:
Why cant we APPLY wht i termed ASSEMBLAGE ANALYSIS OF THE HANDSHAKES?
HOW DO WE DO THAT?
Assemble 2 persons and ask them to MUTUALLY handshakes each other; how many handshake produced? 1? You're a fool! It's 2 handshakes! Go back to the details of the quest! (It says: '...everyone shook hands with everybody ELSE') This could translate to giving same gesture to EACH guest present in same manner...cleared?
Now assemble 3 persons...how many hand shakes? 6? Gud! What about 4 persons? 9? Great!
Now it goes thus:
1 person, O shake
2 persons; 2 shakes
3 persons; 6 shakes
4 persons; 9 shakes
5 persons; 20 shakes
6 persons; 30 shakes
7 persons; 42 shakes
8 persons; 56 shakes
9 persons; 72 shakes
10 persons; 90 shakes
11 persons; 110 shakes
12 persons; 120 shakes
THE MAGIC:
IT'S SIMPLE IMAGINARY; close ur eyes, assemble pupils and intruct them to handshake EACH other (Not One another ooo)
Gud night profs
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by cao(f): 12:30am On Jul 20, 2015
nwaanambra1:
With two people (A and B), there is one handshake
(A with B).

With three people (A, B, and C), there are three handshakes
(A with B and C; B with C).

With four people (A, B, C, and D), there are six handshakes
(A with B, C, and D; B with C and D; C with D).


In general, with n+1 people, the number of handshakes is the sum of the first n consecutive numbers: 1+2+3+ ... + n.


[size=18pt]in this case, the answer is '15'
[/size]

IF U R A GAMBLER - THIS FIGURE IS A SURE BET! wink



Don't think am a genius, am just like THOMAS EDISON! cool wink if u understand what i mean lipsrsealed grin wink
Actually 3 people will have 6 handshakes, 4 people will have 12 handshakes. With the exception of 2 people, which will be one handshake. The general logic is n (n - 1), where n is the number of people. Look, when in doubt, count with your ten fingers. So in this case using that we have n (n - 1) = 120 -> n2 - n - 120 = 0. Using the quadratic formula, we get 11.446 or -10.466. I'm guessing there were 11 folks and some of them decided to add 10 extra handshakes because they felt like it.
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Asad69(m): 12:30am On Jul 20, 2015
How does this help in raising the value of naira in naija?? undecided
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by cao(f): 12:34am On Jul 20, 2015
Asad69:
How does this help in raising the value of naira in naija?? undecided
Maybe if they knew how to solve simple maths equations that didn't involve embezzlement, we'd all be in a better place...
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by BrightyDan: 12:41am On Jul 20, 2015
Iamdagreatguy:
Weekend brain drill. The first to get the answer wins a prize:

At a birthday party, everyone shook hands with everybody else. There were 120 handshakes. How many people were at the party?
Hmmmm..........
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by lagbaja(m): 12:55am On Jul 20, 2015
16 people shook hands.

This is a permutation problem. 16 people with 2 combnation

16!/2!(16-14)!=16!/2!*14!=16*15/2=120
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Balkan(m): 1:11am On Jul 20, 2015
Is it in Nigeria?
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Nobody: 1:12am On Jul 20, 2015
Answer: there are 16 people in total. If 2, 0+1; if 3, 0+1+2; if 4, 0+1+2+3; ...... And so on

1 Like

Re: Weekend Brain Drill: Can You Solve This In 30 secs? by AYGR8tz(m): 1:14am On Jul 20, 2015
[/color] wink[color=#006600]op not in the right mind. In my own voice; what i no be...i no pretend to be it.
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Nobody: 1:17am On Jul 20, 2015
Answer: there are 16 people in total. If 2, 0+1; if 3, 0+1+2; if 4, 0+1+2+3; ...... And so on. I.e 0+....+(n-1)
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by umarshatty(m): 1:21am On Jul 20, 2015
60

2 Likes

Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Nobody: 1:24am On Jul 20, 2015
Ridhwan1:
This's realy puzzling!
Well i wont go 'still' unnotice without droping the litle my brain could produce (at least for tonight)
FIRSTLY MY ANSWER IS 12-GUESTS EVENT!
HOW? fine gud question!
But b4 anything, pls understand that I'm not mathmatician...I read Mass Comm!
NOW TO FORM THE FORMULAR:
Why cant we APPLY wht i termed ASSEMBLAGE ANALYSIS OF THE HANDSHAKES?
HOW DO WE DO THAT?
Assemble 2 persons and ask them to MUTUALLY handshakes each other; how many handshake produced? 1? You're a fool! It's 2 handshakes! Go back to the details of the quest! (It says: '...everyone shook hands with everybody ELSE') This could translate to giving same gesture to EACH guest present in same manner...cleared?
Now assemble 3 persons...how many hand shakes? 6? Gud! What about 4 persons? 9? Great!
Now it goes thus:
1 person, O shake
2 persons; 2 shakes
3 persons; 6 shakes
4 persons; 9 shakes
5 persons; 20 shakes
6 persons; 30 shakes
7 persons; 42 shakes
8 persons; 56 shakes
9 persons; 72 shakes
10 persons; 90 shakes
11 persons; 110 shakes
12 persons; 120 shakes
THE MAGIC:
IT'S SIMPLE IMAGINARY; close ur eyes, assemble pupils and intruct them to handshake EACH other (Not One another ooo)
Gud night profs
Check your dictionary for the meaning of Handshake. No offence though, just an advice to unravel the puzzle in your mind.
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by rastle(m): 1:31am On Jul 20, 2015
There are five (5) people at the party, using permutation and combination method, 5! = 120 i.e 5x4x3x2x1=120, combining the number of hand shakes of 5 people results to 120 times. Engineers will understand what i mean.

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Re: Weekend Brain Drill: Can You Solve This In 30 secs? by femi4: 1:42am On Jul 20, 2015
meshacha1:
12 people will shake hands 11 times each
then, 11 X 12 people = 121
Abeg wetin come be 11x11?
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by femi4: 1:44am On Jul 20, 2015
chloride6:
Mathematically, this is just permutation and Combination

X!/(X-R!R!) equals 120

Where

R is equal to 2

If x! Divides X-2!

We have x times x-1 divided by 2 equals 120

Which is x squared minus x equals 240

Which is a quadratic equation with a,b,c equal to 1, -1 and -240


Solving we have,

X equals 16 and -15

Since we can't have -15 people

Your answer is 16




Where is my gift OP?
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Threemg: 2:16am On Jul 20, 2015
Ridhwan1:
This's realy puzzling!
Well i wont go 'still' unnotice without droping the litle my brain could produce (at least for tonight)
FIRSTLY MY ANSWER IS 12-GUESTS EVENT!
HOW? fine gud question!
But b4 anything, pls understand that I'm not mathmatician...I read Mass Comm!
NOW TO FORM THE FORMULAR:
Why cant we APPLY wht i termed ASSEMBLAGE ANALYSIS OF THE HANDSHAKES?
HOW DO WE DO THAT?
Assemble 2 persons and ask them to MUTUALLY handshakes each other; how many handshake produced? 1? You're a fool! It's 2 handshakes! Go back to the details of the quest! (It says: '...everyone shook hands with everybody ELSE') This could translate to giving same gesture to EACH guest present in same manner...cleared?
Now assemble 3 persons...how many hand shakes? 6? Gud! What about 4 persons? 9? Great!
Now it goes thus:
1 person, O shake
2 persons; 2 shakes
3 persons; 6 shakes
4 persons; 9 shakes
5 persons; 20 shakes
6 persons; 30 shakes
7 persons; 42 shakes
8 persons; 56 shakes
9 persons; 72 shakes
10 persons; 90 shakes
11 persons; 110 shakes
12 persons; 120 shakes
THE MAGIC:
IT'S SIMPLE IMAGINARY; close ur eyes, assemble pupils and intruct them to handshake EACH other (Not One another ooo)
Gud night profs

I won't take any offenses should you tell me you are in JSS3 or SS1. Because I trust you are yet to gain admission to study secretarial study.
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by fuoski(m): 2:29am On Jul 20, 2015
It was 5 person
Its simply 5!
Which is 5*4*3*2=120
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Emyogalanya: 2:37am On Jul 20, 2015
If the party hold im Liberia there'll be no handshake cos none will attend the guy go eat him cake alone. But if na Nigeria na 15 ppl with the celebrate go dey there equal to 16 ppl now lets solve it if celebrant welcome him guests he will shake 15 hands now make the 15 guests stay for line like say they want play match 1 - 15 if numb 1 shake others na 14 number 2 no need to shake number one again he will shake only 13 ppl.... So from celebrant you get 15, 14, 13. 12...... 3. 2. 1 Down to the last man the last man no go shake another person cos all of them don already shake am plus the celebrant
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Djtm(m): 3:13am On Jul 20, 2015
lol. The answer is 5. All the people on the first page are not mathematically oriented or simply did not pass through secondary school.
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Djtm(m): 3:16am On Jul 20, 2015
rastle:
There are five (5) people at the party, using permutation and combination method, 5! = 120 i.e 5x4x3x2x1=120, combining the number of hand shakes of 5 people results to 120 times. Engineers will understand what i mean.

I guess majority of the posters here are "mass comm" our business admin peeps. See peeps calculating and analysing and still getting 60. every math student knows that 5! is 120

1 Like

Re: Weekend Brain Drill: Can You Solve This In 30 secs? by boribori(m): 4:10am On Jul 20, 2015
Their hands begin dey pain them and them come go home crying.
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by ValentineMary(m): 4:40am On Jul 20, 2015
The ans is 6. 6-1=5 getting 5! We have 120
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Medsimon01(m): 5:29am On Jul 20, 2015
5 people ase there using permutation 5!=5*4*3*2*1=1205 people ase there using permutation 5!=5*4*3*2*1=1205 people ase there using permutation 5!=5*4*3*2*1=120
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by kikiano4(m): 5:44am On Jul 20, 2015
16...
cos d 1st pesn will gt 15 handshakes.d 2nd having had a hand shake with d 1st pesn will gt 14 more ..so if u add d hand shakes downwards ..u will have(15+14+...3+2+1) to give 120
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by Situation001(m): 5:51am On Jul 20, 2015
kelvyn7:


u sef think am nau

How can just 5 person's in a room shake 120times if they are to shake each other just once?

5persons will shake only 10times.

or draw 5 points on the ground and connect them. then count the number of connections cheesy


but if u draw 16points and connect each one to the other gives 120 connections

or use this formula
n (n-1 )
-------
2


it's actually a progression :
1 = 0 (add thes two numbs givs d next answer)
2 = 1 (add thes two numbs givs d next answer)
3 = 3 (add thes two numbs givs d next answer)
4 = 6
5 = 10
6 = 15
7 = 21
8 = 28
9 = 36
10 = 45
11 = 55
12 = 66
13 = 78
14 = 91
15 = 105
16 = 120
I reason with you.. My answer should be 120 possible order of handshakes..
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by JoshboboT: 6:12am On Jul 20, 2015
16 is the answer.
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by freeDR(m): 6:16am On Jul 20, 2015
Answer is 12.
Each person shakes 11 times.
However, there is repetition of handshakes if each person takes turn to shake round. Therefore, the repeated handshakes would have to be subtracted from the total number of handshakes to give 120.
12 x 11 = 132.
132-12 = 120
Therefore, there were a total of 120 handshakes from 12 individuals.
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by babatunde31: 6:17am On Jul 20, 2015
5 people cux 5! is 120
Re: Weekend Brain Drill: Can You Solve This In 30 secs? by jony247(m): 6:22am On Jul 20, 2015
5 permutation, combination

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