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# A case of expanding wrongly watch

1. Basically, I attempted a GCSE module 5 exam, today. To which I scored a reasonable 67% (A*), but there was one question which I assumed I had expanded wrongly. But the mark scheme gave no clues, except for the fact that the answer was 4(x+1) or 4x +4

The question is:

8(x + 1)(2x – 3)
______________
2(2x – 3)

the underlining represents the division symbol. Any ideas. I expanded the top brackets with each other and then multiplied each expression by 8. and for the bottom expression i mutliplied the 2x-3 by 2, and divided????

The radius of the sphere is 4 cm.
The radius of the base of the cone is 6 cm.
The volume of the sphere and the volume of the cone are equal.
Calculate the height, h, of the cone.

//////////
I got the 2 first 2 marks: (Volume of sphere =)

where you write out each formula, with the numbers added in so 4/3 PI 3^3, etc. But then I attempted to work out the value of h by combining the sphere volume with the cone volume. E.G 64PI/3= 1/3*PI*6^2*H, but this didn't work any ideas???
2. 1) Don't expand, cancel the (2x-3) on top and bottom and then simplify.
3. 2) Volume of sphere =
4. top expands to 16x^2-8x-24, factorising to 4(4x-6)(x+1)

so the fraction is 4(4x-6)(x+1)/(4x-6)... = 4(x+1) = 4x+4
5. (Original post by f45)
Basically, I attempted a GCSE module 5 exam, today. To which I scored a reasonable 67% (A*), but there was one question which I assumed I had expanded wrongly. But the mark scheme gave no clues, except for the fact that the answer was 4(x+1) or 4x +4

The question is:

8(x + 1)(2x – 3)
______________
2(2x – 3)

the underlining represents the division symbol. Any ideas. I expanded the top brackets with each other and then multiplied each expression by 8. and for the bottom expression i mutliplied the 2x-3 by 2, and divided????

The radius of the sphere is 4 cm.
The radius of the base of the cone is 6 cm.
The volume of the sphere and the volume of the cone are equal.
Calculate the height, h, of the cone.

//////////
I got the 2 first 2 marks: (Volume of sphere =)

where you write out each formula, with the numbers added in so 4/3 PI 3^3, etc. But then I attempted to work out the value of h by combining the sphere volume with the cone volume. E.G 64PI/3= 1/3*PI*6^2*H, but this didn't work any ideas???
You slipped up on the volume of the sphere. It should be 256pi/3 not ...
top expands to 16x^2-8x-24, factorising to 4(4x-6)(x+1)

so the fraction is 4(4x-6)(x+1)/(4x-6)... = 4(x+1) = 4x+4
Your first line of work is completely pointless... you've just expanded and re-factorised it slightly differently.

You should just cancel the (2x-3) on the top and bottom straight away.
7. (Original post by tomthecool)
Your first line of work is completely pointless... you've just expanded and re-factorised it slightly differently.

You should just cancel the (2x-3) on the top and bottom straight away.
wtf?!

you're right lol. cant believe I didn't see that......i feel so stupid now

I just assumed it was an A level type Q where you need to expand everything and shuffle it around a bit before you can cancel....didn't see it was GCSE.

damn lol
8. 67% for an A*... I have totally lost my confidence in the British education system...
67% for an A*... I have totally lost my confidence in the British education system...
Likewise...that's bloody shocking! Not like this in my day...
10. Care to take my maths gcse for me.

Perhaps, you'd like to revise 9subjects, to get an A/A* in each.

Yes, 67% is low, however the pressure students are under nowadays is far greater than it was back then. Especially when exam boards such as Edexcel attempt to trip people at every possibility, with their lack of co-ordination and poorly devised curriculums. It's a wonder anyone Excels.

NB: Thank you to those who helped, rather than playing the "Failing Education" card.
11. Back then?

Coffem took 11 GCSE's like many people on this board.

67% should not be A*. End of.

There are some people who most definitely can achieve 95% on these papers, that is who should get an A*. Not someone who gets 67*...
12. (Original post by Totally Tom)
Back then?

Coffem took 11 GCSE's like many people on this board.

67% should not be A*. End of.

There are some people who most definitely can achieve 95% on these papers, that is who should get an A*. Not someone who gets 67*...
Pfft, with the introduction of modules. Yes, this allows people to break down the course, but it also means you have to hit high in every test. Let me give you the grade boundaries for the two previous tests.

Mod 1: 59/63 A* (Data handling)
Mod 3: 103/115 A* (surds, quadratic's, a kind of taster for module 5.

Module 5, is worth 50% of the course. It involves everything from trig to proofs to quadratics.

Your given 1h 15mins each, to complete non/ calc and calc papers.

Yes 67% is low, but due to the pressure of the exam, where silly mistakes cost you vital marks is it any wonder there being lowered. Yes, the intelligent ones will complain of such grade boundaries. But for those, who don't spend half their time calculating the angles of the dining room table. It provides us with a target which is reachable, it allows us to work harder in the fact, taht we may able to acheive a higher grade than expected.

It's a simple case of psychology, if the garde boundary for an A* is 90% OVERALL, and you end up with an A in a module, it essentailly means you have to hit the high 90s in the remaining exams. Too many would be perturbed to even bother.

I find it extremely irritating, when people belittle other people's grades. Perhaps BECAUSE YOU were dealt a harsh card, you decide to put down the whole education system in an attempt to feel better. How childish...
13. (Original post by f45)
Perhaps BECAUSE YOU were dealt a harsh card, you decide to put down the whole education system in an attempt to feel better. How childish...

no, i don't think that's it at all. for the people who did do really well and got A*s at gcse when it was harder, it's belittling *them* when you say that 67% is an A* these days, it becomes not an achievement but an average, you cant say that gcses are 'hard' ...and it's ridiculous anyway because a levels are so much harder and gcses in no way prepare you for them, i wish they were harder just had a huge reality check, first AS exam is in 2 weeks ..wohoo...!
14. Err I hate to point it out, but I sat 11 GCSEs and got an A* in all of them, and this was 3 years ago! Hence I know full well the pressure students are under, indeed I daresay that right now I'm under substantially more pressure than you are. I am not belittling any of your achievements, but let's face it, 67% for an A* is ridiculous. In my year it was 90% in a pair of linear exams, i.e. none of this module malarkey.

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Updated: April 20, 2008
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