Overclockers UK Forums > Life > General Discussion Noob ratio maths help

 29th Oct 2013, 11:16 #1 Lokai Capodecina     Joined: Jun 2008 Location: Wakefield Posts: 16,562 Noob ratio maths help Looking for a little assistance with a maths questions for someone that hasn't studied in 18 years - Taking two figures (380 ppm carbon dioxide and 1750 ppb methane), express the ratio of co2 to ch4 in the format x: 1, where x is a whole number given to two significant figures. If someone could point me in the right direction it would be greatly appreciated.
 29th Oct 2013, 11:19 #2 ~>Dg<~ Caporegime   Joined: Jun 2006 Location: Notts Posts: 26,663
 29th Oct 2013, 11:31 #3 dl8860 Wise Guy     Joined: Jul 2010 Location: W9 Posts: 1,330 If you divide the larger number by the smaller number when both are in equal units, the number you get is the 'x' you are looking for. Intel G4560 | ATI HD6950 | Nexus 6P
 29th Oct 2013, 11:39 #4 The Dread Pirate Capodecina     Joined: Aug 2007 Location: Outside in the bushes Posts: 15,794 Do Your own Damn Homework! Reach into your bag of tricks and pull another one...
 29th Oct 2013, 12:07 #5 rubberduck Wise Guy   Joined: Feb 2004 Posts: 2,384 1750 ppb = 1.75 ppm So 380/1.75 = 217.14 So i guess the answer is 217.14 : 1
 29th Oct 2013, 12:13 #6 Lokai Capodecina     Joined: Jun 2008 Location: Wakefield Posts: 16,562 Great, thanks for your help, i wasn't converting the methane to ppm from ppb which is where i was going wrong.
29th Oct 2013, 12:17   #7
Freakbro
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Quote:
 Originally Posted by rubberduck 1750 ppb = 1.75 ppm So 380/1.75 = 217.14 So i guess the answer is 217.14 : 1
Except it asks for a whole number to 2 significant figures, not 2 decimal places - which wouldn't be a whole number anyway.

So the answer would be 220 : 1

But well spotted on the ppb I hadn't noticed that

 29th Oct 2013, 12:36 #8 Rudeboy1 Hitman   Joined: Sep 2013 Posts: 542 567
29th Oct 2013, 14:04   #9
Spunkey
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Quote:
 Originally Posted by Freakbro Except it asks for a whole number to 2 significant figures, not 2 decimal places - which wouldn't be a whole number anyway. So the answer would be 220 : 1
Doesn't 'significant figures' mean 'integer', not nearest factor of 10? I made the answer 217:1

29th Oct 2013, 14:22   #10
Freakbro
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Quote:
 Originally Posted by Spunkey Doesn't 'significant figures' mean 'integer', not nearest factor of 10? I made the answer 217:1
No, significant figures means just that, the first set of numbers starting with one that is not zero, then you round up as normal.

So 655,464 to 3 significant figures would be 655,000
to 2 significant figures would be 660,000
and to 1 significant figure would be 700,000

Last edited by Freakbro; 29th Oct 2013 at 14:26.

 29th Oct 2013, 15:02 #11 Spunkey Capodecina     Joined: Oct 2002 Location: The land of milk & beans Posts: 12,554