Jeff Miller

GMAT OFFICIAL GUIDE PS – Water consists of hydrogen and oxygen…

Water consists of hydrogen and oxygen…

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