# MATHS HELP!

Found 18th Apr 2009
How would I find the volume of this? Got me really confused might seem easy to you but I didn't really listen to the instructions.

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Original Poster

work out the volume of the largest one, then the inner 'hole', then take it away?

3x8?...

area of outer circle times 8 minus area of inner circle times 8

Original Poster

sancho1983;4965750

work out the volume of the largest one, then the inner 'hole', then take … work out the volume of the largest one, then the inner 'hole', then take it away?

can't believe i didn't think of that :?.

Outside Diameter Pi * 3squared * 8 = 226.19
Inside Diameter Pi * 1.5squared * 8 = 56.55 (should be 56.54 but rounds up?)
169.64 (this should be 169.65

And the answers right thanks alot stuck for hours repped :thumbsup:

Original Poster

dontdothatagain;4965819

3x8?...

First thing I tried wouldn't make sense becuase the volume would too big because you wouldn't be counting the big hole through the middle.

Original Poster

nibb211;4965820

area of outer circle times 8 minus area of inner circle times 8

Not good with areas so I use the Pi & radius method?

Volume of whole cylinder is 226.285 cubic metres, volume of hole is 56.571 cubic metres, so yr answer is 169.714. Go ]here

i resat gcse maths a few years ago, so here goes...

first of all you need to find the radius which is half the length of the diameter, so the radius would be 3.

then using the pythagorus button (PI), or entering 3.14 so...

pi x r x r x h or 3.14 x 3 x 3 x 8 = 226.08 cm3 then possibly divide that by 2 and that should give you the answer of:

113.04cm3

hope this is right for you...

pi * 3/2 squared etc gives you the area i was just being lazy when i wrote it sorry lol

Banned

find a loo roll and measure, then fill with water, then muliply it by the difference of this measurement and the loo roll

Original Poster

kingy58;4965868

Volume of whole cylinder is 226.285 cubic metres, volume of hole is … Volume of whole cylinder is 226.285 cubic metres, volume of hole is 56.571 cubic metres, so yr answer is 169.714. Go ]here

That seems to be wrong go here handymath.com/cgi…cgi.
Knew the answer just wanted the method don't like cheating.
The answer btw is 169.65

texfitz;4965869

i resat gcse maths a few years ago, so here goes...first of all you need … i resat gcse maths a few years ago, so here goes...first of all you need to find the radius which is half the length of the diameter, so the radius would be 3.then using the pythagorus button (PI), or entering 3.14 so...pi x r x r x h or 3.14 x 3 x 3 x 8 = 226.08 cm3 then possibly divide that by 2 and that should give you the answer of:113.04cm3hope this is right for you...

That gives me the volume if the hole wasn't there I see where your getting at though thanks

nibb211;4965875

pi * 3/2 squared etc gives you the area i was just being lazy when i … pi * 3/2 squared etc gives you the area i was just being lazy when i wrote it sorry lol

Ah finally I understand thanks and no worries.

aye sorry, kingy is right

pi x radius squared gives vol without hole then subtract

pi times (3/2)squared and multiply by8 to give ans

Original Poster

Seems kingy got it wrong the correct answer is 169.65.

Original Poster

kt21;4965923

pi x radius squared gives vol without hole then subtractpi times … pi x radius squared gives vol without hole then subtractpi times (3/2)squared and multiply by8 to give ans

Exactly what got me the answer

yay!!

Got the old brain cells working again.

Original Poster

Lol, thanks everyone for the attempts appreciate it soo much :), off to do the next bit shouldn't be going on addictive HUKD :oops:

Banned

Met-Cast;4965982

Lol, thanks everyone for the attempts appreciate it soo much :), off to … Lol, thanks everyone for the attempts appreciate it soo much :), off to do the next bit shouldn't be going on addictive HUKD :oops:

Original Poster

LOL the toilet roll idea still made me laugh thanks.

Got another one :oops: what do I do with the 2 diameters which are on two sides of a cuboid?

Original Poster

Think your right there.

Not diameters just width and length.

Good God..if were talking about Maths at this time and Quidco isnt involved then I'm bringing the AK47 out....:w00t:

Jumpingphil;4967803

OK, I'm outta here. Goodnight. :thumbsup:

lol...have a good one dude :thumbsup:

Original Poster

Goodnight mate :thumbsup:.
Sorry being lazy heres a pic.

Original Poster

I worked out the hole but was confused on the whole thing thought you had to still use Pi.
Goodnight thanks mate :thumbsup: