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


The ratio, by mass, of hydrogen to oxygen is 2:16
This means that, for every 2 grams of hydrogen, there are 16 grams of oxygen.
2 + 16 = 18
So, for every 18 grams of water 2 grams are hydrogen, and 16 grams are oxygen.
In other words, 16/18 of water is oxygen.
Simplify fraction to say: 8/9 of water is oxygen.

Approximately how many grams of oxygen are there in 144 grams of water?
Since we know that 8/9 of water is oxygen, we can write:
Weight of oxygen = (8/9)(144) = 128

So, there are 128 grams of oxygen in 144 grams of water.

Answer: D

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


oxygen present = (16/18)*144 = 128
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Re: Water consists of hydrogen and oxygen, and the approximate [#permalink]
Is hydrogen water useful for the human body? I want to buy a hydrogen water generator. But not yet decided. I read an article, which is very useful. But still in thought.
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Re: Water consists of hydrogen and oxygen, and the approximate [#permalink]
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Re: Water consists of hydrogen and oxygen, and the approximate [#permalink]
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