Water consists of hydrogen and oxygen, and the approximate

Question

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

Bunuel · Accepted Answer

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.

geno5 · Answer

2 parts hydrogen 16 parts oxygen=18 Total parts

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

D

avohden · Answer

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

Finally apply factor to the part that is oxygen-----> 8*16=128

aeglorre · Answer

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.

PareshGmat · Answer

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

ScottTargetTestPrep · Answer

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.

nkmungila · Answer

The ratio are 2:16
then the oxygen content = 16/18*144
 = 32*4
=128

nigina93 · Answer

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)

BrentGMATPrepNow · Answer

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

amarsinha · Answer

oxygen present = (16/18)*144 = 128

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Water consists of hydrogen and oxygen, and the approximate

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