Current Year 11 thread mark III (woo!) / Year 12 2012/13

Original post by Zozzy

I'm revising for edexcel calculator maths tomorrow and I've got stuck on a question I was wondering if anybody could help me out by explaining how to do this to me.

So I'm doing similar shapes.

Q.) Two prisms, A and B, are mathematically similar.
The volume of prism A is 12,000 cm3
The volume of prism B is 49, 152cm3
The total surface area of prism B is 9,728cm2
Calculate the total surface area of prism A

I got the answer 4806.324 which is wrong. Some help would be really appreciated because I'm really stuck with this one XD.

OK, If things are mathematically similar it means they must have the same ratio of sides and things, but they can be different lengths, e.g. a 6x8 rectangle turning into a 12x16 rectangle.

By dividing the volume of Prism B - 49152cm2 by the volume of Prism A - 12,000cm2, we know how much bigger it is. In this case, it is 4.096 times bigger. Now, we can divide the surface area of Prism B (9,728) by 4.096 to calculate the surface area of Prism A.

My answer was 2375cm2, though I'm not sure this is right - we didn't cover this much in my syllabus.

Reply 6483

shyamshah

12

Original post by g.k.galloway

Okay..I prefer calc to non calc as I don't trust my calculations lol

It also means more shape and space - Which I love :smile:

Yeah same, but luckily I think all my calculations were correct on te=he paper yesterday, I hope the paper tomorrow is similar to the paper yesterday :smile:

Reply 6484

Alexx53

Original post by Zozzy

I'm revising for edexcel calculator maths tomorrow and I've got stuck on a question I was wondering if anybody could help me out by explaining how to do this to me.

So I'm doing similar shapes.

Q.) Two prisms, A and B, are mathematically similar.
The volume of prism A is 12,000 cm3
The volume of prism B is 49, 152cm3
The total surface area of prism B is 9,728cm2
Calculate the total surface area of prism A

I got the answer 4806.324 which is wrong. Some help would be really appreciated because I'm really stuck with this one XD.

(12,000/49,152)

gives you the volume ratio from B to A

(12,000/49,152)^\frac{2}{3}

gives you the surface area ratio from B to A

(12,000/49,152)^\frac{2}{3}*9,728 = 3800cm^2

gives you the surface area of Prism A

(edited 11 years ago)

Reply 6485

Grammar Kid

that break i took is a nightmare i cant get myself to work again :frown:

maths tommorow seems like it might be me trying to it with limited revision then shock myself into doing revision for geography and history :eek:

not a good plan

Reply 6486

Dayum, WHAT IS THIS GYPSY BLACK MAGIC?!

Reply 6487

I don't feel nervous about this Maths as I only need a low mark to get an A* thanks to my other Units. I am just really nervous about the German exams though...

Anyone had a listening/reading exam in any language before?

Reply 6488

Original post by AwkwardLemur

Dayum, WHAT IS THIS GYPSY BLACK MAGIC?!

ummm what gypsy black magic??? :moo:

Reply 6489

Alexx53

Original post by AwkwardLemur

I don't feel nervous about this Maths as I only need a low mark to get an A* thanks to my other Units. I am just really nervous about the German exams though...

Anyone had a listening/reading exam in any language before?

I've done reading/listening and it was very easy. They spoke really slowly :smile:

I'm doing German too but I'm not that nervous for them. How have you done in your controlled assessments so far?

(edited 11 years ago)

Reply 6490

Zozzy

2

Original post by Alexx53

(12,000/49,152)

gives you the volume ratio from B to A

(12,000/49,152)^\frac{2}{3}

gives you the surface area ratio from B to A

(12,000/49,152)^\frac{2}{3}*9,728 = 3800cm^2

gives you the surface area of Prism A

ah this makes sense now :smile:

, thanks very much for the help

Reply 6491

Original post by NomNomNom :)

ummm what gypsy black magic??? :moo:

Just working out that maths question in a freakishly simple manner.

Reply 6492

Original post by AwkwardLemur

I don't feel nervous about this Maths as I only need a low mark to get an A* thanks to my other Units. I am just really nervous about the German exams though...

Anyone had a listening/reading exam in any language before?

yup! spanish...I was really scared I was going to have a coughing fit in the listening..but I didn't, so it was fine :h:

as for the exam itself...well :tongue:

Reply 6493

Well, I got two A*'s in the Writings (28 and 27 I think) and an A* (26) and an A (can't remember) in the Speakings.

We did the listening and reading mocks and I scraped B's. :s-smilie:

I'm hoping to scrape an A in German all together, what about you?

Reply 6494

Original post by AwkwardLemur

Just working out that maths question in a freakishly simple manner.

oh okay, lol :smile:

Sometimes when I get the right answer but with a really long winded method..and the person next to me gets it in one line of working, I get annoyed :tongue:

does anyone else get that or is it just me?

Reply 6495

Original post by NomNomNom :)

oh okay, lol :smile:

Sometimes when I get the right answer but with a really long winded method..and the person next to me gets it in one line of working, I get annoyed :tongue:

does anyone else get that or is it just me?

All the time, haha.

Anyway, our school had a horror story with the French listening exam (luckily I didn't take French). It was in one of those temporary structures - the giant tent/marquee type things. Anyway, there was traffic noise outside, people couldn't hear it properly and the tape broke half way through the exam!

Reply 6496

Original post by AwkwardLemur

All the time, haha.

Anyway, our school had a horror story with the French listening exam (luckily I didn't take French). It was in one of those temporary structures - the giant tent/marquee type things. Anyway, there was traffic noise outside, people couldn't hear it properly and the tape broke half way through the exam!

no!!! what happened after? :eek:

did anyone hear about that thing in China when then they don't let any traffic at all near schools during exams and they block roads. They take their exams really seriously :biggrin:

Reply 6497

Alexx53

Original post by AwkwardLemur

Well, I got two A*'s in the Writings (28 and 27 I think) and an A* (26) and an A (can't remember) in the Speakings.

We did the listening and reading mocks and I scraped B's. :s-smilie:

I'm hoping to scrape an A in German all together, what about you?

I've got A*'s in both writings and speakings (don't remember the marks), and I'm I'm taking German for A-Level so I want to try and get an A* overall :smile:

Reply 6498

Original post by NomNomNom :)

no!!! what happened after? :eek:

did anyone hear about that thing in China when then they don't let any traffic at all near schools during exams and they block roads. They take their exams really seriously :biggrin:

Well, parents just rang in and complained and I think the students have the choice to resit. Yeah, I saw that on the BBC haha, there was a girl who goes to school and then comes home and studies for 6 hours before bed.

Alexx; good effort! I'm sure you'll do fine then - you could get A's, maybe even high B's in these exams and get an A* overall. Don't know about your board, but ours is a 60%/40% CA/Exam split. :smile:

Reply 6499