So you think your good at maths??

[6m$SexGod]

Just like the title says, if you are any good, then please answer the following equations.

And please show your working as so we can seperate the cheats!

Donation Codes are up for grabs!

1.

The Surface area A of a steel cylinder is given by the formula,

A=2(pie)r2+2(pie)rh

R is the radius and H is the Height

A) Find the required radius if A = 12500mm2, and h = 150mm

B) Determine the number of 2.5ltr tins of paint that are needed to coat 500 cylinders with a thickness of 20 microns

2.

A water trough has sloping sides of length 500mm making it triangular in cross section with vertical ends. The Width at the top of the trough is 600mm and the length is 2.0m

A) Calculate the maximum capacity of the trough, giving your answer accurate to the nearest ltr!

B) Find the depth of the water when the trough is half full.

More Questions to follow! :thumbs:

[BIGRICK]

working out -

eeny + meeny (miny) = mo.

Mo = 6

:bleh:

:haha:

[BRR]

i'm not good at math but i can tell you this: you fail at english

pie = A baked food composed of a pastry shell filled with fruit, meat, cheese, or other ingredients, and usually covered with a pastry crust.

Pi = 3.14159265358979323846...

[BIGRICK]

MMmmmmmmm Pie :P

[chrispy]

if i had paper nearby id solve those, but i dont :P

[herojuana]

is that meant to be 2(pi)r^2? as in r squared, rather than r x 2

[BIGRICK]

is that meant to be 2(pi)r^2? as in r squared, rather than r x 2


Oooooh, check you out!!!!! :ninja:

:thumbs:

[Cheeky]

is that meant to be 2(pi)r^2? as in r squared, rather than r x 2
I have no idea what you said, but....GO SAM!! :yay:

[6m$SexGod]

Sam yes it is meant to be pi r2(squared)

So is anyone going to have a go at solving them?

[theaft3rglow]

Nice try.....trying to get us to help you with your homework :glare:
I am working on it right now....but I am not sure about the thickness of 20 microns part. Gimmie a lil bit and I will try.

is 12500mm2 supposed to be 12500mm^2 (squared)?

[ZERAT]

rofl

ask me 2 years ago

i was a sharp maths brain then :haha:

[Flipchic]

get r, using the formula A=2(pi)r^2+2(pi)rh then substitute the values.... its hard to type the whole solution here...

[herojuana]

Sam yes it is meant to be pi r2(squared)

So is anyone going to have a go at solving them?

no

at least not me... if i am going to do anything that uses my brain, it should almost certainly be uni work. for that reason i cant justify and so am off to the xbox :P

[theaft3rglow]

God I am terrible at this now. I have (most likely improperly) gotten this far:

12500mm^2=2(pi)r^2+2(pi)r150mm

12500mm^2=4(2pi)r^2+r(150)

12500mm^2=4(2pi)+2r^2(150)

I would assume that if this was true...then the next step would be somthing like:

15625000mm=4(2pi)+2r^2(150)

15625000mm=8pi+2r^2(150)

15625000mm=8pi+2^r2
-------------
150mm

Thats as far as i got....But there is too much of a fraction for this to go any further...

So I probably made a wrong turn somewhere, Ill heep working on it.

[Flipchic]

if A = 2(Pi)r^2 + 2(Pi)rH , r =?

somethin like:

A = 2(pi)r^2+2(pi)rh

A = [2(Pi)] [r^2 + rh]

A/2(Pi) = r^2 + rh

A/2(Pi) = r (1^2 + H)

A/2(Pi) = r
-------
1+H

:chow2:

[6m$SexGod]

Haha, i have the answers to these, if you would like help let me know, it just quite good to get people having a go at some equations

Flip, i'll right it out in easier terms.

12500 = 2x3.14r^2 + 2x3.14rx150

That make it easier?

[theaft3rglow]

if A = 2(Pi)r^2 + 2(Pi)rH , r =?

somethin like:

A = 2(pi)r^2+2(pi)rh

A = [2(Pi)] [r^2 + rh]

A/2(Pi) = r^2 + rh

A/2(Pi) = r (1^2 + H)

A/2(Pi) = r
-------
1+H

:chow2:

That is a far better conclusion than I got....I havent done ANY math in like...5 years....AND I was in calc.2 my senior year. I SUCK:angry2:

[Flipchic]

Haha, i have the answers to these, if you would like help let me know, it just quite good to get people having a go at some equations

Flip, i'll right it out in easier terms.

12500 = 2x3.14r^2 + 2x3.14rx150

That make it easier?

lol..

[12500][2(3.14)]
---------------- = r
1 + 150

12500(6.28)
----------- = r
151

r = 519.86755 :rah:

That is a far better conclusion than I got....I havent done ANY math in like...5 years....AND I was in calc.2 my senior year. I SUCK:angry2:

:hehe: well scott says its not right.. but hey, it made me look like i really know math.. lol

[bfj]

2(pi)r^2 + 2(pi)rh - 12500 = 0

(pi)r^2 + 150(pi)r - 6250 = 0

solve using quadratic form

x = -b +/- SQRT(b^2+4ac)
--------------------------
2a


x = -150(pi) +/- SQRT((150(pi))^2+4(pi)*6250)
----------------------------------------------
2(pi)


x = 12.26652199

[6m$SexGod]

2(pi)r^2 + 2(pi)rh - 12500 = 0

(pi)r^2 + 150(pi)r - 6250 = 0

solve using quadratic form

x = -b +/- SQRT(b^2+4ac)
--------------------------
2a


x = -150(pi) +/- SQRT((150(pi))^2+4(pi)*6250)
----------------------------------------------
2(pi)


x = 12.26652199


Now for just the 2nd question and you get codes!

And i got 12.3 for my answer, but i rounded up, so it is deviated, but thats ok, was only 13 out in the end!

Oh and whats your msn, so if i need any help? lol :P

[bfj]

part 2 :P

20 micron = .02 mm

vol = area 8 height
volume of paint needed for 1 cylinder = 12500*.02 = 250mm^3

250mm^3 = .00025L
*500 = .125L

1 can of paint =2.5L

so you need 5% of one can for 500 cylinders

[6m$SexGod]

How sure are you with that answer???

[Brick Shit House]

How sure are you with that answer???

hey no confusing him so you don't have to give him the code ;)

[Flipchic]

2(pi)r^2 + 2(pi)rh - 12500 = 0

(pi)r^2 + 150(pi)r - 6250 = 0

solve using quadratic form

x = -b +/- SQRT(b^2+4ac)
--------------------------
2a


x = -150(pi) +/- SQRT((150(pi))^2+4(pi)*6250)
----------------------------------------------
2(pi)


x = 12.26652199

:chow2:

[6m$SexGod]

hey no confusing him so you don't have to give him the code ;)

No the reason i am asking is, that i have had to engineers at work get to totally different answers.

And to get the code hes got to answer the 2nd question! :P

[bfj]

How sure are you with that answer???

the math is correct, i'm just not sure of your assumptions :P

that or the question is designed to try and fool you



answering question antoher way.

1 litre = 1,000,000 mm^3

.02*12500 = 250mm^3 * 500 cylinders = 125,000mm^3

125,000/2,500,000 = .05 or 5% of 1 can

[Janitor Carl]

question 1:

A = 2(pi)r^2 + 2(pi)rh
A = 2(pi)(r^2+rh)
A = 2(pi)r(r+h)

A/2(pi) = r(r+h)

re-arrange to get:

r^2 + rh - (A/2(pi)) = 0 and subsitute values for (pi), and h: (crude value for pi = 3.14)

r^2 + 150r - (12500/(2*3.14)) = 0
r^2 + 150r - 1990 = 0

Factorize:
(r+150)*(r-13) = 0

so r = -150 or r = 13

I choose r = 13mm.

if A = 12500mm squared.
500 A = 6250,000 mm squared.
1mm = 1000 micron, so 20 micron = 0.02mm
Volume of paint required = Area x thickness
= 6250,000mm x 0.02mm
= 125000 ml of paint.
2,5 litres = 2500 ml
125000/2500 = 50 tins of paint.

If I´m bored tomorrow I might answer question number two.
;o)

[bfj]

if A = 12500mm squared.
500 A = 6250,000 mm squared.
1mm = 1000 micron, so 20 micron = 0.02mm
Volume of paint required = Area x thickness
= 6250,000mm x 0.02mm
= 125000 ml of paint.
2,5 litres = 2500 ml
125000/2500 = 50 tins of paint.


1mL = 1000 mm^3

[bfj]

if you have 2 engineers that can't answer that, you need to find some new engineers :S

[6m$SexGod]

See what i mean,

I got

Pi x 12.32^2 = 475mm^2

150x2xPi r = 150x2x3.14x12.3 = 11586.6mm^2

11586.6+475 = 12061.6mm^2

12061.6x500 = 6,030,800

VOL = 6,030,800 x(20/1000)

= 120.616ltrs / 2.5 = 48.27 tins of paint

[bfj]

See what i mean,

I got

Pi x 12.32^2 = 475mm^2

150x2xPi r = 150x2x3.14x12.3 = 11586.6mm^2

11586.6+475 = 12061.6mm^2

12061.6x500 = 6,030,800

VOL = 6,030,800 x(20/1000)

= 120.616ltrs / 2.5 = 48.27 tins of paint

why would you go back to calculate area when it's already given? 12500mm^2 exactly

1 Litre = 1,000,000 mm^3 not 1,000mm^3

1 millilitre = 1,000 mm^3

[ZERAT]

See what i mean,

I got

Pi x 12.32^2 = 475mm^2

150x2xPi r = 150x2x3.14x12.3 = 11586.6mm^2

11586.6+475 = 12061.6mm^2

12061.6x500 = 6,030,800

VOL = 6,030,800 x(20/1000)

= 120.616ltrs / 2.5 = 48.27 tins of paint


but remember to say 49 tins of paint ;)

[bfj]

seriously find some new engineers :S

[6m$SexGod]

Well 1 engineer got 5% and the other got that! So.... i was on here looking for the majority, but others have said the same..

Now im screwed!

[bfj]

Well 1 engineer got 5% and the other got that! So.... i was on here looking for the majority, but others have said the same..

Now im screwed!

both answers are essentially the same, it's the conversion that's throwing you off.

look up some tables for volume unit conversions :P

[bfj]

now gimme my code damnit :P


i'll do question 2 when you send me code for question 1
:bleh:

[6m$SexGod]

No you get code for doing both questions!

And another engineer has come out at 5%, they are taking the piss out of the person that said 48 tins. lol

[bfj]

No you get code for doing both questions!

And another engineer has come out at 5%, they are taking the piss out of the person that said 48 tins. lol

fine see below

part A)

trough volume = 0.5*base*height*length
=.5*600*400*2000
=240,000,000 mm^3

1,000,000 mm^3 = 1 L

so 240 L total capacity



part B)


depth of water when 120L

120,000,000 = .5*base*height*length

120,000,000 = .5 * 600 * height * 2000

height = 200 MM

[Brick Shit House]

See what i mean,

I got

Pi x 12.32^2 = 475mm^2

150x2xPi r = 150x2x3.14x12.3 = 11586.6mm^2

11586.6+475 = 12061.6mm^2

12061.6x500 = 6,030,800

VOL = 6,030,800 x(20/1000)

= 120.616ltrs / 2.5 = 48.27 tins of paint

With 50 he accounted for the sloppy ness of the painter and the and if it is applyed by spray the wind loss as well :haha:


Sorry i suck at math

[Infidel]

If I wasn't so lazy I could do this for ya.

[joker]

A=2(pie)r2+2(pie)rh A=surface area is 2 + height is 2 so we known surface surrounding is 4, or in aother words radius is 4, do inside of the ( ) what we do to one side we have to do to the other pie, pie we can eliminate because they all or the same so basically it is O, so what we have left is rh because they cannot be elimenated because they r not the same, so we have is 4rh

[6m$SexGod]

bfj in your answer any reason for putting

.5*600*400*2000

Why did you choose 400 not 500??

I'm confused now?

[bfj]

bfj in your answer any reason for putting

.5*600*400*2000

Why did you choose 400 not 500??

I'm confused now?


i thought you finished the answers to this already :P

you have to split the triangle into 2 pieces to get the height. using pythagorean (sp?) theorm you solve for the height. 300^2 + x^2 = 500^2, x =400


now gimme my codes :P

[jay]

i thought you finished the answers to this already :P

you have to split the triangle into 2 pieces to get the height. using pythagorean (sp?) theorm you solve for the height. 300^2 + x^2 = 500^2, x =400


now gimme my codes :P

:haha: I was just about to write this for Scott.. now I know who to come to when I have problems with my calculus homework.

[bfj]

:haha: I was just about to write this for Scott.. now I know who to come to when I have problems with my calculus homework.

MATHLETES RULE!!!


:smiley:

[6m$SexGod]

Yeah I had totally forgot about that! You will get your codes tomorrow fella on msn, and I also have a couple more questions that I do not know how to do! :)

[Spork!!!]

The trough isn't 1/2 full, its 1/2 empty you optomistic fool. ;)

[6m$SexGod]

The trough isn't 1/2 full, its 1/2 empty you optomistic fool. ;)

shall i put that in my answer? lol:thumbs:

[Nazkyn]

So you think you're good at maths? Perhaps you would like to do my maths assignment for me? :)

[6m$SexGod]

What are the questions, i can have a go!

Im a bit rusty some times, like shown above!

[bfj]

WHERE'S MY CODE!

:snob: