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Junior Cert 2011 : Maths Paper 2

Cakes.

Monday 13th June 2011.
Afternoon 2:00-4:00/4:30

All discussion and questions about Paper 2 goes here.

Good luck everyone!

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Indiego

her0fire wrote: »

2 theorems in consecutive years has never happened so don't count on pythagoras to come up.
Anyone know how to do paper 1 Q 2 ( c ) ?
It was the one with the sets and there was one other question, it was express t in terms of s and r

for q2 c, (this is really hard to explain btw, so sorry if i make no sence

), but,

for part one, where you have to find the minimum value of #(PUQ)', it means you have to find the smallest possible number that would work in the part of the venn diagram outside of P and Q, to do this, you can assume that the 16 in P, and the 6 in Q and not part of the intersection, and that P and Q have nothing in the intersection, meaning that P + Q = 16 + 6, which is 22, meaning that the leftover 8 (30-22) would be #(PUQ)'.

for part two, you have to find the maximum value of #(PUQ)', meaning you have to find the largest possible number that would make sence in the part of the venn diagram outside of P and Q, and still add up to 30. To do this you can assume that the 6 in Q is also a part of P, meaning it would be in the intersection, meaning # P + Q = P (because Q is part of P) would be 16 only. This means that #(PUQ)' would be 30 - 16, which is 14.

Did that make sense?

for part three, you have to proove that u = p + x, x being the largest possible number outside of P and Q in the diagram, which mean you can assume its the same situation as in part (ii), where Q is also a part of P, this would mean that u = x - q + p + q, or, u = p + x

for the other question, t^2 - s = r, this is how you do it:
t^2 - s = r
t^2 = r + s (move s across the equal sign and change the sign)
t = (sqrt) r + s (find the square root of both sides, meaning that t^2 becomes t, and r + s becomes (sqrt) r + s

Hope I helped

cantanstrophe

Indiego wrote: »

for q2 c, (this is really hard to explain btw, so sorry if i make no sence ), but,

for part one, where you have to find the minimum value of #(PUQ)', it means you have to find the smallest possible number that would work in the part of the venn diagram outside of P and Q

This almost caught me out - in the frenzy of getting the paper, I missed the apostrophe, and answered the question differently, but I changed it soon afterwards :pac:

Indiego

cantanstrophe wrote: »

This almost caught me out - in the frenzy of getting the paper, I missed the apostrophe, and answered the question differently, but I changed it soon afterwards :pac:

hahah its a good thing you noticed :L
I took one look at that question, expecting the usual sets question, realised how odd it was, and skipped it :rolleyes: i left it till the very end, and my then id thought about it so much it made complete sense :pac:

her0fire

Indiego wrote: »

for q2 c, (this is really hard to explain btw, so sorry if i make no sence ), but,

for part one, where you have to find the minimum value of #(PUQ)', it means you have to find the smallest possible number that would work in the part of the venn diagram outside of P and Q, to do this, you can assume that the 16 in P, and the 6 in Q and not part of the intersection, and that P and Q have nothing in the intersection, meaning that P + Q = 16 + 6, which is 22, meaning that the leftover 8 (30-22) would be #(PUQ)'.

for part two, you have to find the maximum value of #(PUQ)', meaning you have to find the largest possible number that would make sence in the part of the venn diagram outside of P and Q, and still add up to 30. To do this you can assume that the 6 in Q is also a part of P, meaning it would be in the intersection, meaning # P + Q = P (because Q is part of P) would be 16 only. This means that #(PUQ)' would be 30 - 16, which is 14.

Did that make sense?

for part three, you have to proove that u = p + x, x being the largest possible number outside of P and Q in the diagram, which mean you can assume its the same situation as in part (ii), where Q is also a part of P, this would mean that u = x - q + p + q, or, u = p + x

for the other question, t^2 - s = r, this is how you do it:
t^2 - s = r
t^2 = r + s (move s across the equal sign and change the sign)
t = (sqrt) r + s (find the square root of both sides, meaning that t^2 becomes t, and r + s becomes (sqrt) r + s

Hope I helped

Ahh thanks man, I can't believe I got the epxress T one wrong.
I think I got the rest right though, the only 1 I'm unsure was the tax one above the sets question
Was 2% levy, was that to find the 2% of 40,000?

Desire.

her0fire wrote: »

Was 2% levy, was that to find the 2% of 40,000?

Yeah, 2% of her gross income.

her0fire

Desire. wrote: »

Yeah, 2% of her gross income.

Would you then add that on top of the tax she has to pay and minus it from her gross income to get the answer?

rainaa

can you guys post what answer you got to the one with the girl who makes 40,000 a year?

just want to make sure i got it right.

Desire.

I would actually love if Pythagoras' Theorem came up. Just looked at it there, it's so simple!

her0fire wrote: »

Would you then add that on top of the tax she has to pay and minus it from her gross income to get the answer?

Exactly.

omg a kitty

her0fire wrote: »

Would you then add that on top of the tax she has to pay and minus it from her gross income to get the answer?

yes you add the 2% levy to her net tax and take whatever you got when you added them away from her gross income

juncert

Thought this was paper 2 thread lads

can do anything about paper 1 now:D

CradBear

My maths teacher said that theorem 7,5 and 4 or 3 should be coming up this year :pac:

AnnKiins

CradBear wrote: »

My maths teacher said that theorem 7,5 and 4 or 3 should be coming up this year :pac:

Your better off learning all of them to be safe c:

ohdechertig

For question 3(a), I forgot to square root the t, so I left it as t^2 = r+s.

What would I get out of 10?

phenomenale

ohdechertig wrote: »

For question 3(a), I forgot to square root the t, so I left it as t^2 = r+s.

What would I get out of 10?

My guess is that that would be taken as a blunder (-3) so 7/10.

Can deductions be asked in the proofs or is is just the 10 theorems?

Desire.

phenomenale wrote: »

Can deductions be asked in the proofs or is is just the 10 theorems?

The deductions can be asked too.

Slow Show

I was always under the impression you wouldn't have to be asked to prove the deductions, you'd just need to know what they mean...they come up frequently in part A's, but what with that theorem being very likely to come up as a part B, I wouldn't expect to see a part A in them. Then again, they could be asked in a part C so it's best to know them.

Desire.

Slow Show wrote: »

I was always under the impression you wouldn't have to be asked to prove the deductions, you'd just need to know what they mean...

2008, Question 4, Part B, ii -- "Prove that a line through the centre of a circle perpendicular to a chord bisects the chord."

Colm!

Desire. wrote: »

2008, Question 4, Part B, ii -- "Prove that a line through the centre of a circle perpendicular to a chord bisects the chord."

Huh? That's a theorem, Theorem 8 on the syllabus.

I agree with Slow Show. You won't be asked to "prove" deductions as you would theorems but might be asked to use them to solve problems. So, know them.

scipsss

Eh you all might think this is strange but i don't know what pythagorous's theorem is ? i thought it was like h squared + r squared = l squared or something like that ?

Desire.

Colm! wrote: »

Huh? That's a theorem, Theorem 8 on the syllabus.

Ah, you're right. Someone wasn't listening in class. Just learned it there though, it's easy.

Thanks!

Colm!

scipsss wrote: »

Eh you all might think this is strange but i don't know what pythagorous's theorem is ? i thought it was like h squared + r squared = l squared or something like that ?

Quick description in MS Paint:

That's not how you prove the theory, but it should show you how to apply it in exam questions. I'll try and find the proof as it's a bit long and I can't really draw it up in Paint.

omg a kitty

scipsss wrote: »

Eh you all might think this is strange but i don't know what pythagorous's theorem is ? i thought it was like h squared + r squared = l squared or something like that ?

Quick summary of what Colm explained:
If you have a right angled triangle, and they tell you the two sides that make up the right angle, you can find out what the hypotenuse is(the side opposite to the right angle).
Say if it was 3 and 4, so
3^ + 4^ = hypotenuse^
9 + 16 = hypotenuse^
25 = hypotenuse^
sq.root of 25 = hypotenuse
5 = hypotenuse

^ means squared

They could come up in Paper 2 Q5, but the question might not be that direct, and I think it could come up in Q3 aswell

Slow Show

Oh wow I'd love if Pythagoras somehow came up in a part C, so wonderfully easy

. They tend to save it for trigonometry though, sigh. Ummm the standard proof for good ole Pythag is....

OK, I just did a quick search online and the proof of the theorem is quite elusive, I know I found all the theorems and their proofs online one day, if I stumble across it I'll stick it up here. But anyway, I don't actually use the standard proof for Pythagoras, I found it really hard to remember, I use a method using a square...it's kinda hard to explain, but it's wonderfully easy and if anyone wants me to I'll try explain it. You're really unlikely to be asked on it though, sadly.

ScummyMan

Gah, project maths

Ye are all so lucky to be doing a normal Paper 2, Project Maths is so impossibly hard

We dont even know how many questions there will be, all we have to go on is 1 sample paper :eek:

KaBooom

Im getting worried about paper 2, cant wrap my head around these theorems at all, didnt pay much attention to them in class and I dont know any of them off by heart.. Instead of learning them today, I calculated the highest grade i can get if I skip all the theorems questions :L

King John The Last

Explain it! I want to remember Pythrogas and I cant remember my teachers way.

buyer95

Does anyone know like the key theroems to know? Like what are likely to be asked... I dont know all of them that well and I'm kind of panicking now, no time to learn them all... Any tips?

Slow Show

It's hard to explain, I'll write it out and try scan it up or something in a bit, it can count as studying. :pac:

Desire.

buyer95 wrote: »

Does anyone know like the key theroems to know? Like what are likely to be asked... I dont know all of them that well and I'm kind of panicking now, no time to learn them all... Any tips?

If you had to learn one theorem, learn the circle theorem, number seven.

JC2011girl

Can anyone give me a brief description of the different questions for example
Q6- statistics? Thanks