:DI wish I was trolling you my friend, but I am indeed ethnic and good at maths.
So maybe it wasn't so easy, and you're just good at it?
I'm not sure that ethnicity has anything to do with it, unless perhaps certain people do have special genes that increases their ability at maths while at the same time reducing their tendency to be modest.
Yeah, I've never been any good at 'seeing' the factorisation - especially in my head without a piece of paper to scribble on.
It's not a case of "seeing" the factorisation. There's a method which works every time.
Say you have a quadratic equation of the form x^2 + bx +c then you can factorise it by finding two numbers which multiply to get c and add to get b
For n^2 -n -90
b=-1 and c=-90
After a bit of thinking, you find that 9 and -10 multiply to give -90 and add to give -1.
Once you now this you can just write the equation in the form (n+9)(n-10)
If this doesn't work, then the equation doesn't factorise nicely.
For quadratic equations of the form ax^2 +bx + c (one where the number in front of x^2 is not 1) the process is a little less straightforward, but there's still a method which I won't go into now.
This question has nothing to do with quadratic equations or factorisation!
It's a simple probability question.
Are you stupid or are you trolling us???!?!!
Please answer me.
I think the poster was responding to me.
You don't have to factorise anything for the purpose of this question, but the result you get is a quadratic equation, which you could solve via factorisation if you felt like it.
I'm pretty sure the second part of the question would be to solve the equation as it's quite straightforward.
I think it's fairly simple, with a bit of thinking about. Others think its a bit trickier, and that's fair enough. However, what isn't OK is everyone, including the papers, making out like it is some sort of really far out-there, unsolvable question by all but Stephen Hawking, when it quite clearly isn't. It's a puzzler, for sure, but not that much of a puzzler...
Well Ive seen enough of the thread (2 pages) to see Im obviously the dimbo who cant understand the question let alone understand the working out and explanations.
So many people here are obviously smug that its such an easy question.
Well Ive seen enough of the thread (2 pages) to see Im obviously the dimbo who cant understand the question let alone understand the working out and explanations.
So many people here are obviously smug that its such an easy question.
I have always felt that I was good at maths and I love a puzzle but this confused me.
In my day, the question would have ended with "How many sweets were in the bag?"
It looks like these days they give you the answer and ask you to prove it
Well Ive seen enough of the thread (2 pages) to see Im obviously the dimbo who cant understand the question let alone understand the working out and explanations.
So many people here are obviously smug that its such an easy question.
Yes, you can almost smell the mathematical testosterone can't you? . Unfortunately some people on forums get a kick out of rubbishing the abilities of others. You get the same on grammar and spelling threads.
Thats what I thought and I woujld have struggled enough with that, I was thinking around the 18 mark,, but the second bit just bamboozled me.
Me too.
I understand that the chanced of the first sweet being Orange is 6 over 10 and that the chance of the second also being orange is 5 over 9 and if you multiply the two together you get 1 over 3
but where the hell did the 90 come from?
The only numbers we have to go on in this equation are 1, 3 and 6.
would be able to do the algebra, but wouldn't know how to construct the equation calculating the probability as one third.
Yes, definitely a constructing the equation problem for most people. I've tried to tutor a few people (a long time ago) and it's pretty much always this bit that throws them - recognising what kind of question it is and making the initial steps more so than the actual resolving the equation.
Not a clue on the number of sweets to begin with, so I just took part (b) on its own. I thought if n² - n - 90 = 0, then obviously n² - n = 90. That meant n had to be bigger than nine, and it just so happened that ten worked straight away. Fairly easy to work out the first part given that. Did I do it the wrong way?
Not a clue on the number of sweets to begin with, so I just took part (b) on its own. I thought if n² - n - 90 = 0, then obviously n² - n = 90. That meant n had to be bigger than nine, and it just so happened that ten worked straight away. Fairly easy to work out the first part given that. Did I do it the wrong way?
You did it the same way as me and ignored the sweets bollocks completely
Not a clue on the number of sweets to begin with, so I just took part (b) on its own. I thought if n² - n - 90 = 0, then obviously n² - n = 90. That meant n had to be bigger than nine, and it just so happened that ten worked straight away. Fairly easy to work out the first part given that. Did I do it the wrong way?
You did. You first have to prove why you get n² - n - 90 = 0, which you have to write 6/n * 5/(n-1) = 1/3...if you move things around you should show the exact same stuff ( n² - n - 90 = 0)
I understand that the chanced of the first sweet being Orange is 6 over 10 and that the chance of the second also being orange is 5 over 9 and if you multiply the two together you get 1 over 3
but where the hell did the 90 come from?
You can multiply both sides of the equation by any value so long as it is applied to both sides.
When you multiply both sides by 3 to clear the 1/3 part and multiply out the brackets (I forget the numbers given now) then the 90 comes naturally. Students are (or were) always taught to try to express an equation in the simplest form possible so fractions should always be eliminated where possible. This premise should lead them to the 90 in their simplifying.
If anyone sincerely wants a step by step way through the problem then PM me and I'll keep my condescending manner down to a bare minimum - promise. (I'm rubbish at loads of things and don't get them either - foreign languages, musical aptitude, writing coherently.....I've no reason to feel superior), but if anyone is genuinely interested then read my post on page 1 and PM me the bit where you struggle. I was okay at maths once and I've probably forgotten 90% of everything I learned but I can break down the steps into words and explain it that way if anyone is genuinely struggling and wants to see how it works.
You can multiply both sides of the equation by any value so long as it is applied to both sides.
When you multiply both sides by 3 to clear the 1/3 part and multiply out the brackets (I forget the numbers given now) then the 90 comes naturally. Students are (or were) always taught to try to express an equation in the simplest form possible so fractions should always be eliminated where possible. This premise should lead them to the 90 in their simplifying.
If anyone sincerely wants a step by step way through the problem then PM me and I'll keep my condescending manner down to a bare minimum - promise. (I'm rubbish at loads of things and don't get them either - foreign languages, musical aptitude, writing coherently.....I've no reason to feel superior), but if anyone is genuinely interested then read my post on page 1 and PM me the bit where you struggle. I was okay at maths once and I've probably forgotten 90% of everything I learned but I can break down the steps into words and explain it that way if anyone is genuinely struggling and wants to see how it works.
This is where you lost me
When given the numbers 1,3 and 6 to use in a simple equation, I can get 1,, 2, 3, 6, 9, 12 18 and 24.
Comments
This question has nothing to do with quadratic equations or factorisation!
It's a simple probability question.
Are you stupid or are you trolling us???!?!!
Please answer me.
:DI wish I was trolling you my friend, but I am indeed ethnic and good at maths.
So maybe it wasn't so easy, and you're just good at it?
I'm not sure that ethnicity has anything to do with it, unless perhaps certain people do have special genes that increases their ability at maths while at the same time reducing their tendency to be modest.
It's not a case of "seeing" the factorisation. There's a method which works every time.
Say you have a quadratic equation of the form x^2 + bx +c then you can factorise it by finding two numbers which multiply to get c and add to get b
For n^2 -n -90
b=-1 and c=-90
After a bit of thinking, you find that 9 and -10 multiply to give -90 and add to give -1.
Once you now this you can just write the equation in the form (n+9)(n-10)
If this doesn't work, then the equation doesn't factorise nicely.
For quadratic equations of the form ax^2 +bx + c (one where the number in front of x^2 is not 1) the process is a little less straightforward, but there's still a method which I won't go into now.
I think the poster was responding to me.
You don't have to factorise anything for the purpose of this question, but the result you get is a quadratic equation, which you could solve via factorisation if you felt like it.
I'm pretty sure the second part of the question would be to solve the equation as it's quite straightforward.
Ah. Thanks. That makes more sense.
So many people here are obviously smug that its such an easy question.
I'll thank you for an apology.
I have always felt that I was good at maths and I love a puzzle but this confused me.
In my day, the question would have ended with "How many sweets were in the bag?"
It looks like these days they give you the answer and ask you to prove it
You used trial and error when you factorised. No algorithm. My approach is to use a lookup table and iterate.
Thats what I thought and I woujld have struggled enough with that, I was thinking around the 18 mark,, but the second bit just bamboozled me.
Me too.
but where the hell did the 90 come from?
The only numbers we have to go on in this equation are 1, 3 and 6.
Yes, definitely a constructing the equation problem for most people. I've tried to tutor a few people (a long time ago) and it's pretty much always this bit that throws them - recognising what kind of question it is and making the initial steps more so than the actual resolving the equation.
Epic tweet by Tesco
You did it the same way as me and ignored the sweets bollocks completely
You did. You first have to prove why you get n² - n - 90 = 0, which you have to write 6/n * 5/(n-1) = 1/3...if you move things around you should show the exact same stuff ( n² - n - 90 = 0)
I loved one of the replies
@Tesco Have you any offers on packs of grass seed. We may need them after your delivery van drove over my grass #poorservice
Oh dear
You can multiply both sides of the equation by any value so long as it is applied to both sides.
When you multiply both sides by 3 to clear the 1/3 part and multiply out the brackets (I forget the numbers given now) then the 90 comes naturally. Students are (or were) always taught to try to express an equation in the simplest form possible so fractions should always be eliminated where possible. This premise should lead them to the 90 in their simplifying.
If anyone sincerely wants a step by step way through the problem then PM me and I'll keep my condescending manner down to a bare minimum - promise. (I'm rubbish at loads of things and don't get them either - foreign languages, musical aptitude, writing coherently.....I've no reason to feel superior), but if anyone is genuinely interested then read my post on page 1 and PM me the bit where you struggle. I was okay at maths once and I've probably forgotten 90% of everything I learned but I can break down the steps into words and explain it that way if anyone is genuinely struggling and wants to see how it works.
Your told the probability of choosing the sweets is 1/3. So just integrate n into the probability equation.
At uni there were similar questions in my first year but more complicated like choosing ransoms balls then putting one back etc etc.
This is where you lost me
When given the numbers 1,3 and 6 to use in a simple equation, I can get 1,, 2, 3, 6, 9, 12 18 and 24.
Not 90