Hi there, There's a problem in our 8th grade science book that I don't understand how to solve. Of course the teacher's edition gives me the answer, but with no explanation. Just the answer. Since this subject matter is not my strong suit, I need some help. Question: The specific gravity of liquid hydrogen is 0.07. If the pressure at the bottom of a 50 ft high tank of water is 22 psi, what would be the pressure at the bottom of the same tank if it were filled with liquid hydrogen instead? Book's answer: 1.54 psi (0.07 x 22 psi) The only formulas explained in the text just before this question are specific gravity= density of water/density of water and pressure= force/area I don't think either of these formulas apply to this; however, I may be wrong. And if one does apply, please explain how. Thanks for any help! I can't stand telling kids "that's the answer because the book says it is!"