Need help with math question before Saturday
@vera5d (4004)
United States
February 28, 2008 11:35pm CST
My hubby is studying to take a general math test for new job on Saturday...we've brushed up on the basics like algebra & geometry & all that (it is scary how much i actually remember from my 8th grade algebra class, lol)...but this one question is really stumping us on how to solve and can't seem to find any formula that really explains it...
Here is the question:
A column of water 2.31 feet high exerts a pressure of 1 pound per square inch...How much pressure does a column of 46.2 square feet exert?
Now, my logic is 2.31 = 1/1 so to get 1/1 with the 46.2 sq feet you'd just multiply the two together (2.31 x 46.2) and get an answer of 106.72
But I have no idea if this is right! (Yup, good old practice test with no answer key!) My hubby wants to divide the 46.2 by the 2.31 for an answer of 20...
Any ideas? A formula I should use? A good site filled with this type of math problems and answers?? thanks in advance! we never learned about this in school!
2 people like this
5 responses
@kamran12 (5526)
• Pakistan
29 Feb 08
Hello vera5d,
Your husband is right, the answer is 20!
The formula to determine a fluid pressure on a surface is 'pgh' (rho-gee-aich) i.e Density of fluid x acceleration due to gravity x height of column.
Since fluid is same (water), so density and 'g' will cancel out and the pressure ratio will be equal to ratio of heights of columns which is 46.2/2.31 = 20
2 people like this
@vera5d (4004)
• United States
29 Feb 08
I have verified it with my brother, a mechanic, and a few math high school friends i have on my myspace...it is 20! So you are right!
I hope he does well, too - I am so sick of the job he has now - the new one will be a paycut for 6 months but in a year he'll be making about the same...most importantly though he'll see his family - right now he's working 70 hours a week which is so hard on him, poor guy is always tired...and i really don't get any breaks from the kids other than maybe a half hour for a shower!
2 people like this
@chrislotz (8136)
• Canada
29 Feb 08
I never took this kind of math in school either and since I am 50 years old I wouldn't remember even if we did. But in my opinion, I think your husband is right about dividing 2.31 into 46.2 to get the answer of 20 lbs. per square inch. I could be wrong though so I think you need to evaluate all the responses you get here and then go with the way that most people have said to do it. Good luck with finding out the right answer to this math question, my friend.
2 people like this
@vera5d (4004)
• United States
29 Feb 08
it is hard to remember math after so long...all through school they beat it into your head how much you would use it and need it and everything else...i think other than the basics we learned in grade school the rest has been mostly forgotten. Though we had this crazy algebra teacher in 8th grade, one of those teachers older kids and parents warned you about...she was tough but man it is still stuck in my head to this day...thanks for your response! i can always count on mylotters to help out :)
1 person likes this
@vera5d (4004)
• United States
29 Feb 08
i just remembered that I have 6 math genius friends on myspace...they will probably not respond, but i will post this question there to see if i get any kind of answer on it...
@Grandmaof2 (7578)
• Canada
1 Mar 08
I'm definately following this and would appreciate knowing what the correct answer will actually be. My hubby is usually pretty sharp at figuring these things out and he felt this was a trick question, and didn't really make sense to him. We are both hopping the BR is the right answer good luck folks!!!
@vera5d (4004)
• United States
29 Feb 08
i will share with the hubby and see if it makes sense to him...i am too tired to read the whole thing right now! We have spent the last three nights doing math questions...i fortunately was a huge math nerd...one of my favorite shows as a kid was a pbs math show called square one...we used to do polynomials and calc questions on placemats at our local high school hang out...but psi is not anything I ever learned about or even really thought about other than using the little gauge my dad gave me to check the air in my tires :)
1 person likes this
@drannhh (15219)
• United States
29 Feb 08
I was too pressed for time to read it through and check the calculations myself at the time, but since then, I see that the page is right on target and explains pretty clearly why, as Kamran12 already said by now, your husband was right.
I think he will find the page helpful.
2 people like this
@vera5d (4004)
• United States
29 Feb 08
I didn't even consider that...now even more confusion!! It seems the majority is leaning towards 20...hopefully we'll get an answer here :)
