OT - Need a math wizard.

[Billy Clyde Puckett]

OK I know this is entirely inappropriate, but I have a serious case of brain lock trying to help my 6th grade daughter with her math homework. Can anyone help me set up the formula to solve this problem?

Tank has three different sized valves. If you open only valve A tank empties in 15 minutes, open only valve B and tank empties in 30 minutes, open only valve C and the tank empties in 45 minutes. How long does it take to empty tank of all three valves are opened.

Damn, I feel stupid not being able to do an 11 year old's math. Duh :hitself:

[heydensmom]

LOL don't worry...Can't believe I'm admitting this...but yesterday I was helping my son with his math homework and usually I ace my math classes, but he asked me what 3 step division was......I had no clue...had to look it up to find the answer to help him. I felt like a dumb ass too.

[Pendejo]

11.25 minutes using my "New Math" that I just invented.

[watermock]

Not sure but I have to call the fuel company.

[watermock]

You might think 30minutes, but the question doesn't answer the question of flow at all if all three are opened.

My answer is 30 minutes, approximately.

[yavoon]

its a rate question. pretend the tank has 1 gallon, first valve is 1/15th of a gallon/minute second is 1/30th of a gallon in a minute and third is 1/45th of a gallon in a minute.

common denominator makes it 6/90+3/90+2/90 which gives u 11/90 gallons/minute. which means it takes just under 9 minutes.

hope that all worked out.

[watermock]

The reality is that unless it's pumped the pressure will change. Have him tell the tearcher that.

It'm terrible at math but they don't give the equation a pressure equation.

[Hotrod]

Id just write down that in your opinon opening all 3 valves at the same time would create a pressure valcum which would effect the rate of flow. That being the case its a jacked question.

or you could say 13 minutes whichever you prefer.

[Hotrod]

The reality is that unless it's pumped the pressure will change. Have him tell the tearcher that.

It'm terrible at math but they don't give the equation a pressure equation.

LOL beat me to it .

[watermock]

Tank has three different sized valves. If you open only valve A tank empties in 15 minutes, open only valve B and tank empties in 30 minutes, open only valve C and the tank empties in 45 minutes. How long does it take to empty tank of all three valves are opened.


ok, that was idiotic. Let me try again.

[Hotrod]

Wait it would prolly be less then 10 minutes.

[Lev Vyvanse]

Valve a empties the tank at a rate of 1/15th of the tank per minute, valve B empties the tank at 1/30th per minute, and valve C empties the tank at 1/45th per minute. So add them up to get 2/90 + 3/90 + 6/90 = 11/90 all valves per minute. So 11/90*t(time) = 1 which comes out to 8 1/45 minutes.

[Boobs McGee]

wouldn't it be 15 minutes?

If A only takes 15, and all of them are open, it wouldn't matter because A is the fastest

[Boobs McGee]

now i remember why math was never my strongpoint :P

[Smiling Assassin27]

when in doubt, the answer is always 'C' or '2'...

[smalltowngrll]

wouldn't it be 15 minutes?

If A only takes 15, and all of them are open, it wouldn't matter because A is the fastest


They are all three emptying at the same time...it would be under 15 minutes. Valve A would empty the most because it takes less time to empty it all.

[broncosteven]

I can do Binary Math & figure out how to subnet IP addresses but I cannot do simple multiplication or addition at the poker table.

[Billy Clyde Puckett]

I can gues that it is going to be around 8 minutes, but for the life of me I can't think of what the formula would be . If it was just valve A and valve B, the answer would be 10 minutes as the second drains at half the rate of the first.

Damn that Dave and his diabolical teacher friends :kiddingme

[Boobs McGee]

They are all three emptying at the same time...it would be under 15 minutes. Valve A would empty the most because it takes less time to empty it all.

absolutely correct there! i was hoping for the "outside the box" lucky guess answer. ;D

carry on class

[smalltowngrll]

I can gues that it is going to be around 8 minutes, but for the life of me I can't think of what the formula would be . If it was just valve A and valve B, the answer would be 10 minutes as the second drains at half the rate of the first.

Damn that Dave and his diabolical teacher friends :kiddingme

Are you looking for the algabraic equation?

[Lev Vyvanse]

Valve a empties the tank at a rate of 1/15th of the tank per minute, valve B empties the tank at 1/30th per minute, and valve C empties the tank at 1/45th per minute. So add them up to get 2/90 + 3/90 + 6/90 = 11/90 all valves per minute. So 11/90*t(time) = 1 which comes out to 8 1/45 minutes.

If this were a real life application, you would have to know a lot more information. The rate of release would decrease as the pressure in the tank decreased. This problem would be a differential equation which = really **** hard math.

[Hotrod]

If this were a real life application, you would have to know a lot more information. The rate of release would decrease as the pressure in the tank decreased. This problem would be a differential equation which = really **** hard math.

Thats what I said the actual answer can not be found.

[smalltowngrll]

x=rate
y=time

x/15+x/30+x/45=y

I believe that would be your equation.

[elsid13]

Id just write down that in your opinon opening all 3 valves at the same time would create a pressure valcum which would effect the rate of flow. That being the case its a jacked question.

or you could say 13 minutes whichever you prefer.


Wrong answer, didn't your Greenpeace friends teach you anything. The answer is "Opening the values would release harmful stuff that would harm Mother Earth. Are you some kinda killer, you evil math teacher?"

PS- I can give you the differential equations for flow but I don't think that what they are learning in 6th.

[Hotrod]

Also unless you have 3 people or 3 hands the answer may change depending on which valve you open first and how long it takes you to open each of the two.

[Boobs McGee]

so basically TheTrueOne has the right answer then.

[Hotrod]

Wrong answer, didn't your Greenpeace friends teach you anything. The answer is "Opening the values would release harmful stuff that would harm Mother Earth. Are you some kinda killer, you evil math teacher?"

PS- I can give you the differential equations for flow but I don't think that what they are learning in 6th.

I think it would be ok if you took a match to the contents once they were on the ground. :)

[Lev Vyvanse]

x=rate
y=time

x/15+x/30+x/45=y

I believe that would be your equation.

I'm fairly sure you are wrong.

[smalltowngrll]

Another idea..look at the examples that are being taught with the homework...this should give you a good idea for what the teacher is teaching in the class...and, chances are, the answer will fall in line directly with the topic they are learning.

[Hotrod]

I'm fairly sure you are wrong.

That does not matter shes cute ;D

Either way you cant solve the problem with the info given.

[Blueflame]

Valve a empties the tank at a rate of 1/15th of the tank per minute, valve B empties the tank at 1/30th per minute, and valve C empties the tank at 1/45th per minute. So add them up to get 2/90 + 3/90 + 6/90 = 11/90 all valves per minute. So 11/90*t(time) = 1 which comes out to 8 1/45 minutes.

I believe your least common denominator would be 45; not 90. For the sake of simplicity, let's say it's a 45-gallon tank. Valve "A" would release 3 gallons per minute, Valve "B" would release 2, and Valve "C" would release 1. In total, six gallons per minute would be emptied, which would then take 7 1/2 minutes for 45 gallons.

[yavoon]

I believe your least common denominator would be 45; not 90. For the sake of simplicity, let's say it's a 45-gallon tank. Valve "A" would release 3 gallons per minute, Valve "B" would release 2, and Valve "C" would release 1. In total, six gallons per minute would be emptied, which would then take 7 1/2 minutes for 45 gallons.

30 goes into 45?

[Boobs McGee]

they used to have the answers in the back of the book when I was in school.
Is this still the deal?

[Raider Bill]

Wait a minute here, assume it's a 90 gallon tank, the size doesnt really matter since the valves are all relative, just an easy number to work with.

Valve A flows 6 Gallons per minute
Valve B flows 3 Gallons per minute
Valve c flows 2 Gallons per minute

All 3 open = 11 gallons per minute = 8 2/11 minutes (90/11)

[OrangeShadow]

boy im glad i just finished finals

[Bronco_Beerslug]

I believe your least common denominator would be 45; not 90. For the sake of simplicity, let's say it's a 45-gallon tank. Valve "A" would release 3 gallons per minute, Valve "B" would release 2, and Valve "C" would release 1. In total, six gallons per minute would be emptied, which would then take 7 1/2 minutes for 45 gallons.
:)
I see some 6th grade math is kicking some arse in this thread.

[Bronco_Beerslug]

Wait a minute here, assume it's a 90 gallon tank, the size doesnt really matter since the valves are all relative, just an easy number to work with.

Valve A flows 6 Gallons per minute
Valve B flows 3 Gallons per minute
Valve c flows 2 Gallons per minute

All 3 open = 11 gallons per minute = 8 2/11 minutes (90/11) Yep, 8.18 minutes, which is what, 8 minutes and about 11 seconds?

[Lev Vyvanse]

Wait a minute here, assume it's a 90 gallon tank

Valve A flows 6 Gallons per minute
Valve B flows 3 Gallons per minute
Valve c flows 2 Gallons per minute

All 3 open = 11 gallons per minute = 8 2/11 minutes (90/11)

Yep. my equation was right but I ****ed up the mult. and div.

[watermock]

That does not matter shes cute ;D

Either way you cant solve the problem with the info given.

Yeah, the question doesn't give enough information about the barometric pressure.

I was horrible at algebra, I was a musician and debater. When the tank runs dry you screwed up. The pump will fail if it doesn't have the lubrication. I'm not help, I just call the fuel depot.

[watermock]

I just take a hammer and bang on the side of the tank! Ha! Well, actually a stick, you don't want to release rust. It's very scientific.

[Billy Clyde Puckett]

I'm waiting for LABF to jump in here and say it is Bush's fault and a government agency would give me the answer if the democrats were in power.

Thanks everyone.

I personally would go with some of Hotrod's suggestions, but The True One got her on the right track so she can figure it out on her own from there.

I'll go back to my domino tournament with the other old guys.

[elsid13]

Yeah, the question doesn't give enough information about the barometric pressure.

I was horrible at algebra, I was a musician and debater. When the tank runs dry you screwed up. The pump will fail if it doesn't have the lubrication. I'm not help, I just call the fuel depot.


Singing in the shower and yelling at yourself doesn't make you either a musician or a debater in most peoples' eyes. ;D

[Lev Vyvanse]

I'm waiting for LABF to jump in here and say it is Bush's fault and a government agency would give me the answer if the democrats were in power.

Thanks everyone.

I personally would go with some of Hotrod's suggestions, but The True One got her on the right track so she can figure it out on her own from there.

I'll go back to my domino tournament with the other old guys.

Everything but my final answer was correct raider bill got the right answer.

[watermock]

Singing in the shower and yelling at yourself doesn't make you either a musician or a debater in most peoples' eyes. ;D

Doesn't matter to me at all. I had Scholarhips at Iowa, Morningside, Augustana and IlCC. You know nothing about me.

[Garcia Bronco]

The reality is that unless it's pumped the pressure will change. Have him tell the tearcher that.

It'm terrible at math but they don't give the equation a pressure equation.


Because the give you the rate....pressure is a constant

[Garcia Bronco]

Valve a empties the tank at a rate of 1/15th of the tank per minute, valve B empties the tank at 1/30th per minute, and valve C empties the tank at 1/45th per minute. So add them up to get 2/90 + 3/90 + 6/90 = 11/90 all valves per minute. So 11/90*t(time) = 1 which comes out to 8 1/45 minutes.


I believe this is the correct answer

[watermock]

Hey I was in Mexico with a young girl at the time on vacation. They did give me homework tho Ha!. I don't have a clue but I know you need a common denominator then you divide. Or something.

Can't I just put a stick in the tank to see if I need to call the fuel company?

[watermock]

I used a huge railroad jack to pour out old fuel we were afraid of a fuel shortage and poured bunch of old fuel out. Then I poured about a gallon of fuel stabilizer and had the tanker come in. We got them thar puters to tell us everythang. They do all that cypherin'.

[jbiel]

I believe your least common denominator would be 45; not 90. For the sake of simplicity, let's say it's a 45-gallon tank. Valve "A" would release 3 gallons per minute, Valve "B" would release 2, and Valve "C" would release 1. In total, six gallons per minute would be emptied, which would then take 7 1/2 minutes for 45 gallons.

Valve B would be 1.5 so it would total 5.5 gallons/minute or 8.18 to empty the tank. Raider Bill got it right also, it doesnt matter what the denominator is. The tank could be 1000 gallons if you wanted it to be, either way the answer will be 8.18 minutes...

[Willynowei]

provided all 3 valves are located below the water level, and there is no way air can get into the top of the tank, this is an unanswerable question because all valves will slow to a trickle because of the lack of air pressure inside the container.

However... Assuming the tank is open top :)

Please someone explain to me if I'm wrong, but i think this is how you do it.

15/45t + 30/45t + t = 45?

r = 8.18 minutes

We use the base rate as 45, and measure the other 2 rates according to the base rate. t being time, 45 being the amount of water in the tank, to make it easier.

You could also make an arbitrary number as the amount in the tank i suppose:

15/100t + 30/100t + 45/100t = 100 gallons would work as well.

Answer r = 8.18

[eddie mac]

Everything but my final answer was correct raider bill got the right answer.

Raider Bill should be good at Maths as he's been counting how many days since a Superbowl win???

[Willynowei]

provided all 3 valves are located below the water level, and there is no way air can get into the top of the tank, this is an unanswerable question because all valves will slow to a trickle because of the lack of air pressure inside the container.

However... Assuming the tank is open top :)

Please someone explain to me if I'm wrong, but i think this is how you do it.

15/45t + 30/45t + t = 45?

r = 8.18 minutes

We use the base rate as 45, and measure the other 2 rates according to the base rate. t being time, 45 being the amount of water in the tank, to make it easier.

You could also make an arbitrary number as the amount in the tank i suppose:

15/100t + 30/100t + 45/100t = 100 gallons would work as well.

Answer r = 8.18

lol... it seems this was answered well before i posted.

I guess i should read others posts before posting.

But atleast I'm right :~ohyah!:

[Billy Clyde Puckett]

Thanks again everyone.

[broncogary]

Raider Bill should be good at Maths as he's been counting how many days since a Superbowl win???

Hey, that's more than 6th grade math there, bubba. :~ohyah!: