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Water consists of hydrogen and oxygen, and the approximate

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Water consists of hydrogen and oxygen, and the approximate  [#permalink]

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New post 07 Dec 2012, 06:23
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Water consists of hydrogen and oxygen, and the approximate ratio, by mass, of hydrogen to oxygen is 2:16. Approximately how many grams of oxygen are there in 144 grams of water?

(A) 16
(B) 72
(C) 112
(D) 128
(E) 142
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Re: Water consists of hydrogen and oxygen, and the approximate  [#permalink]

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New post 07 Dec 2012, 06:26
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Walkabout wrote:
Water consists of hydrogen and oxygen, and the approximate ratio, by mass, of hydrogen to oxygen is 2:16. Approximately how many grams of oxygen are there in 144 grams of water?

(A) 16
(B) 72
(C) 112
(D) 128
(E) 142


Since the ratio, by mass, of hydrogen to oxygen is 2:16, then oxygen is 16/(2+16)=8/9 of mass of water.

Therefore there are 144*8/9=128 grams of oxygen in 144 grams of water.

Answer: D.
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Re: Water consists of hydrogen and oxygen, and the approximate  [#permalink]

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New post 04 Jan 2013, 20:12
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Walkabout wrote:
Water consists of hydrogen and oxygen, and the approximate ratio, by mass, of hydrogen to oxygen is 2:16. Approximately how many grams of oxygen are there in 144 grams of water?

(A) 16
(B) 72
(C) 112
(D) 128
(E) 142


2 parts hydrogen 16 parts oxygen=18 Total parts

2x+16x=18x---->144/18, x=8 8*16=128 parts oxygen

D
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Re: Water consists of hydrogen and oxygen, and the approximate  [#permalink]

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New post 02 Oct 2013, 11:37
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Simplify the ratio of hydrogen, oxygen to total from 2:16:18 to 1:8:9. Divide total grams of water by the sum of the parts of the ratio to determine the approximate multiple of the ratio to use = 144/9=16

Finally apply factor to the part that is oxygen-----> 8*16=128
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Re: Water consists of hydrogen and oxygen, and the approximate  [#permalink]

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New post 19 Dec 2013, 10:04
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Walkabout wrote:
Water consists of hydrogen and oxygen, and the approximate ratio, by mass, of hydrogen to oxygen is 2:16. Approximately how many grams of oxygen are there in 144 grams of water?

(A) 16
(B) 72
(C) 112
(D) 128
(E) 142



I solved this very sloppily.. 144/18 = 8... 8 * 16 = 80 + 48 = 128..

I do not know if this approach works in general (it even took me almost 4 minutes to solve it..), but it worked here.
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Water consists of hydrogen and oxygen, and the approximate  [#permalink]

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New post 11 Sep 2014, 02:56
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Given ratio = 2:16 = 1:8 = Hydrogen : Oxygen

Let the quantity = x (by mass)

x + 8x = 144

x = 16

Amount of Oxygen = 144-16 = 128

Answer = D
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Re: Water consists of hydrogen and oxygen, and the approximate  [#permalink]

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New post 09 Jun 2016, 14:02
1
Walkabout wrote:
Water consists of hydrogen and oxygen, and the approximate ratio, by mass, of hydrogen to oxygen is 2:16. Approximately how many grams of oxygen are there in 144 grams of water?

(A) 16
(B) 72
(C) 112
(D) 128
(E) 142


Solution:

We are given that the ratio of hydrogen to oxygen in water, by mass, is 2 : 16. Using our ratio multiplier we can re-write this as 2x : 16x. We can now use these expressions to determine how much oxygen is in 144 grams of water.

2x + 16x = 144

18x = 144

x = 8

Since x is 8, we know that there are 16 x 8 = 128 grams of oxygen in 144 grams of water.

Answer D.
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Re: Water consists of hydrogen and oxygen, and the approximate  [#permalink]

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New post 21 Sep 2017, 22:37
The ratio are 2:16
then the oxygen content = 16/18*144
= 32*4
=128
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Re: Water consists of hydrogen and oxygen, and the approximate  [#permalink]

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New post 22 Jun 2018, 07:04
Hydrogen:oxygen=2:16, we know that in 144 ml of water we have 18x of both hy and oxy. So we set an equation,
18x=144
x=8,
8*16=128 (D)
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Re: Water consists of hydrogen and oxygen, and the approximate &nbs [#permalink] 22 Jun 2018, 07:04
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