ScoobyDoo555

My poor daughter's been tearing her hair out with a sequencing problem she's been given today by her teacher. I'll await to speak with this teacher once I've calmed down, but suffice to say that it would appear as though support has not been provided. (I'm in Education as well, so my urge to vent is high as I know what should have happened).

Anyhoo. The sequence is for a people ringing each other on the phone: how many times can a single call be made to each individual.
She's then got to work out the sequence and a "rule" that would apply.

Now, I'm not a thick person by any means, however I'll be the first to admit that my Maths was an epic fail. I struggled to get my GCSE 'C' 25 years ago. Since then, when I needed calculations, I've used a boffin.

Aynbody care to shed any light on what the sequence/rule is?

ie 1 person = 0 conversation
2 people = 1 conversation
3 people = 2 conversations

etc
etc

What's the feckin rule??


ASAP would be extremely appreciated - she's been up since 6.30am.....

Thanks in advance,

DAn

Myles

iTrader: (40)

Can I suggest that the answer may be that the number of calls=number of callers - 1.

Please bear in mind that I took my maths GCSE in '88 (I think!) and got a D. Retook in '89 then got an E. Im sticking with the D.

Chip

The rule is minus 1, ie x=p-1, where p is the number of people and x is the number of conversations. e.g. for 3 people. p=3 therefore x=2

Don't blame me if its wrong as my daughter (A level maths)typed that out.

boxst

Rule is all previous numbers added together.

1 = +0

2 = 1 + 0 = 1

3 = 2 + 1 = 3

4 = 3 + 2 + 1 = 6

5 = 4 + 3 + 2 + 1 = 10

jods

1 person = A (0 conversations)
2 people = A to B (1 conversation)
3 people = A to B, A to C, C to B (3 conversations!) so I'm no help

ScoobyDoo555

I'm not far behind you mate!!

the sequence she's got so far is :-

1 caller = 0 (can't talk to yourself)
2 callers = 1 conversation
3 callers = 2 conversation (between caller 1 & 2, then caller 2 & 3, and caller 3 & 1)
all the way up 6 callers.

make sense?

TinyTim

iTrader: (3)

It's not, but i'm not in the frame of mind to work it out right now...

ScoobyDoo555

Thanks Boxst
The confusion (down to how the "teacher" has explained it or not) was that method in which the sequence rule has to be shown.

That's what I got......

DAn

TinyTim

iTrader: (3)

Spot on

Myles

iTrader: (40)

Is it the amount of conversations the one person can have with all the others, as that is how I read it? If not, like Johnny Ball Ill have to think again!

SJ_Skyline

http://en.wikipedia.org/wiki/Triangular_number

David Lock

Don't see how that stacks up against the starting example?

Hasn't she got a clever mate she can text?

d

Chip

She'd probably get the number wrong

jods

The sequence of triangular numbers (sequence A000217 in OEIS) for n = 1, 2, 3... is:
1, 3, 6, 10, 15, 21, 28, 36, 45, 55, .... So that supports my answer then - so, either the teacher is some mong "assistant" or the kid wrote the question down wrong?

(not calling your kid a mong - calling the assistant a mong!!)

what would scooby do

You need to factor in the schizophrenics

SJ_Skyline

jods - You quoted me with my fat fingers putting the 3 under the equation

Besides, the equation is also wrong in that to solve for n it should use n-1

jods

Isn't that, by definition 3 conversations???

bioforger

iTrader: (1)

maths *******

Myles

iTrader: (40)

I can't agree enough. The reason I got an E was because our rotund teacher put me off with her fatness. Honest.

boxst

It doesn't, but I think the example is wrong.

ScoobyDoo555

yeh, I mistyped it!!

She would get the phone number right - speed-dial Most deffo not a mong - VERY high SAT scores/bright kid. (but I appreciate the sentiment)
My suspicion is that the question/task either (a) wasn't conveyed properly or (b) not understood, or a combo of both.
Either way - teacher should have CHECKED that the question was understood, and child knew what was expected.

As it turns out, she'd taken the examples too literally and expected the same type of answers to express.
Can't be anything too difficult - she's 11 FFS

All sorted now - thanks to Scoobynet math club!!


Dan


ps 1st rule of math club, is not to talk about math club

bioforger

iTrader: (1)

lol fattist.

jods

So - we're agreed then:
n x (n-1) = x
1 person
1 x (1-1) = 0

2
2 x (2-1) = 2

3
3 x (3-1) = 6

4
4 x (4-1) = 12

etc

boxst

No ... my example.

jods

Crap I'm confooosed myself now - dammit

ScoobyDoo555

I get it now, but I'd be FAR happier showing you how recording studio works at electronics level.
Feckin hate maths

jods

mamoon2

This is what i'm getting but don't know how to apply a rule to it.

This is complicated stuff for an 11 year old

boxst

They are triangular numbers.

I cannot express the formula here, but basically it is the previous answer plus the previous number.

5 = (previous answer (6) + previous number (4)) = 10

6 = (previous answer (10) + previous number (5)) = 15

jods

Seems a bit advanced for an 11 year old!!