n2-n-90=0

[seagulls4ever]

SPOILER BELOW










The chance of getting an orange sweet first time = 6/n where n is the total number of sweets.
Having already taken an orange sweet, the chance of getting an orange sweet next time = 5/(n-1)
The probability of both being orange sweets is one third, so 6/n x 5/(n-1) = 1/3
Or (6x5)/n(n-1) = 1/3
Then 30/(n^2-n) = 1/3
(3x30)/(n^2-n) = 1
90/(n^2-n) = 1
90=n^2-n
n^2-n-90=0

QED

n is obviously 10, but that wasn't the question.
I passed my O level maths in 1985.

Finally someone comes out with the proper answer, although people weren't helped by not being given the actual question in the original post. Of course n = 10, but as you say, that wasn't the question. As you see in these worked answers, 10 doesn't appear in any of them. Wonder how many people claiming how easy it is could actually get the full marks?

 

[studio150]

So for all the brainy people that have solved the puzzle- will it buy you a better car/house/partner

Probably given that job prospects and therefore higher income improve with educational qualifications. A failure to obtain a basic maths qualification will be a bar to many employment options.

 

[Creaky]

Finally someone comes out with the proper answer, although people weren't helped by not being given the actual question in the original post. Of course n = 10, but as you say, that wasn't the question. As you see in these worked answers, 10 doesn't appear in any of them. Wonder how many people claiming how easy it is could actually get the full marks?

I think I'm living in a parallel universe!

The answer was in the original link.

 

[SIMMO SAYS]

I don't understand the question!

I don't understand the answer

 

[SIMMO SAYS]

I think I'm living in a parallel universe!

The answer was in the original link.

View attachment 65872

Is Hannah obese

 

[SIMMO SAYS]

When is the footie going to start

 

[seagullsovergrimsby]

Is Hannah obese

I'm still trying to work out how many sweets Hannah has eaten after she caught the 12.30 from Kings Cross and arrived in Newcastle at 15.30.

 

[easynow]

I remember looking through my old maths textbooks some time ago...i might aswell been looking at hieroglyphics. #incalculatorswetrust

 

[Kosmonaut]

The question was badly worded, it should have been worded thusly:

(a) show that this problem simplifies to the quadratic equation n^2 - n - 90 = 0

(b) calculate n

 

[OzMike]

We got harder back in '76, piece of piss.

 

[Vegas Seagull]

I remember looking through my old maths textbooks some time ago...i might aswell been looking at hieroglyphics. #incalculatorswetrust

Indeed, for many a Maths oral would reflect what we are faced with in life ie standing by the counter ordering tiles sized 15ch by 9cm for a floor 4.23m by 4.75m @ £11.99 and being able to tell the assistant he is hundreds out after he taps away for minutes

 

[Vegas Seagull]

Indeed, for many a Maths oral would reflect what we are faced with in life ie standing by the counter ordering tiles sized 15ch by 9cm for a floor 4.23m by 4.75m @ £11.99 and being able to tell the assistant he is hundreds out after he taps away for minutes

Good point, in fact, just simple stuff by 2 people each naming a high 2 figure no. & seeing who can do it in their head fastest is a good way to uncover who can read & remember and who can think on their feet. Tim Vine and his family do 3x3's for fun after Xmas lunch, if you didn't know so here is today's arithmetic challenge, only head to be used no calcs, no pens, no cheating, lowest seconds/mins wins.
367 x 848 = ?

 

[Norman Potting]

Good point, in fact, just simple stuff by 2 people each naming a high 2 figure no. & seeing who can do it in their head fastest is a good way to uncover who can read & remember and who can think on their feet. Tim Vine and his family do 3x3's for fun after Xmas lunch, if you didn't know so here is today's arithmetic challenge, only head to be used no calcs, no pens, no cheating, lowest seconds/mins wins.
367 x 848 = ?

Tim Vine's Christmas must be a bundle of fun, particularly if you consider his brother Jeremy could be there as well.

 

[Gullflyinghigh]

I can honestly say I would've failed to answer that correctly. Getting that n is 10 is easy enough but after that...yeah, I'd have no chance.

Happily, I've never had a need to do anything like it in the 'real' world, so I think I can accept my failure on this one.

 

[Blue Valkyrie]

I think I'm living in a parallel universe!

The answer was in the original link.

View attachment 65872

Perhaps those in the different universe are on tapatalk, so don't generally click links as it defeats the object of being on tp ?

To them the thread was an equation, and the question given in the OP was to solve it.

 

[Uh_huh_him]

Mrs White at Durrington was a great teacher. Buzzer and I were in the same class in 1985.

You and Buzzer were a couple of years below me then. She was my maths teacher in 83-84.
Yes she was a great teacher... I never got the hang of advanced maths though.

 

[Simster]

The question was badly worded, it should have been worded thusly:

(a) show that this problem simplifies to the quadratic equation n^2 - n - 90 = 0

(b) calculate n

I actually think part b) was more difficult than part a).

 

[Goldstone1976]

So for all the brainy people that have solved the puzzle- will it buy you a better car/house/partner

It should do; it should do; obviously not.

 

[severnside gull]

Worryingly simple

I'm doing pre-GCSE remedial maths with my year 9 granddaughter at the moment because she hasn't been taught basic number properly

 

[severnside gull]

So for all the brainy people that have solved the puzzle- will it buy you a better car/house/partner

Where n is the true percentage pay rise you gave yourself and 0 is the answer you are selling to Joe Public?

Seems to work for CallMeDave