how long will it take to pump the water out of the basement?

eddy2017

Full Member
a tenant needs to pump water out of a flooded basement, using two 50 (gpm) pumps.
The basement has the dimensions shown and is flooded to a depth of 16 inches.
How long will it take to pump the water out of the basement?

I thought about finding the perimeter of this rectangle-shaped basement adding up all dimensions given as a way to start this, but I am not sure it is a good idea. Any hints?>
thank you for you help
eddy

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lev888

Senior Member
a tenant needs to pump water out of a flooded basement, using two 50 (gpm) pumps.
The basement has the dimensions shown and is flooded to a depth of 16 inches.
How long will it take to pump the water out of the basement?

I thought about finding the perimeter of this rectangle-shaped basement adding up all dimensions given as a way to start this, but I am not sure it is a good idea. Any hints?>
thank you for you help
eddy
If you are not sure what to do, how about trying the approach I suggested a while ago?
You are asked about time to do a job and given a rate. Time = ?

eddy2017

Full Member
If you are not sure what to do, how about trying the approach I suggested a while ago?
You are asked about time to do a job and given a rate. Time = ?
t = d/s
time equals distance over rate of speed

lev888

Senior Member
t = d/s
time equals distance over rate of speed
Well, here we are dealing not with distance, but with a job/task of a particular size. How do we measure the size? What are the units? Does the rate units (gpm) tell you anything?

eddy2017

Full Member
Well, here we are dealing not with distance, but with a job/task of a particular size. How do we measure the size? What are the units? Does the rate units (gpm) tell you anything?
gallons per minute.
well, i have distance in ft of the basement and the depth of the water which is 16 inches deep
two pumps that pump 50 gallons of water a minute.
but i dont know what formula i should apply here.

lev888

Senior Member
gallons per minute.
well, i have distance in ft of the basement and the depth of the water which is 16 inches deep
two pumps that pump 50 gallons of water a minute.
but i dont know what formula i should apply here.
What are we measuring in gallons? Time = (size of job)/rate. What is the size?

eddy2017

Full Member
What are we measuring in gallons? Time = (size of job)/rate. What is the size?
the size of the job is the size given for the basement plus the fact that the water is 16 inches deep
40feet, 50feet, 24feet, 22feet.

lev888

Senior Member
the size of the job is the size given for the basement plus the fact that the water is 16 inches deep
40feet, 50feet, 24feet, 22feet.
Yes, but what do we call this quantity? What do we measure in gallons?

eddy2017

Full Member
Yes, but what do we call this quantity? What do we measure in gallons?
water. perhaps finding the volume of the water in the basement. then we will know how many gallons will have to be pumped out. and then once i have the amount of gallons i know that there are two pumps that pumps 50 gallons every minute so multiplying the amount of gallons being pumped at the rate of 50 gallons a minute i will find out the amount of time needed to pump it all out.
but i do not know how to go about finding the volume of water in the basement.
i know that the basement has sort of a rectangular shape in the diagram.
i also know that the volume of a rectangular box, like this basement, is the length times the width times the depth.
but the shape of the basement has me confused.

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lev888

Senior Member
water. perhaps finding the volume of the water in the basement. then we will know how many gallons will have to be pumped out. and then once i have the amount of gallons i know that there are two pumps that pumps 50 gallons every minute so multiplying the amount of gallons being pumped at the rate of 50 gallons a minute i will find out the amount of time needed to pump it all out.
but i do not know how to go about finding the volume of water in the basement.
Yes, volume. Not sure what you mean by "multiplying the amount of gallons". Multiplying by what? Why? What's the _main_ formula? The 'top-down' approach I am pushing tells you to write down the main formula/relationship, then do what it tells you: if you know all variables, then evaluate or solve it. If some variables are not known, then find formulas/relationships for them. Never do random stuff such as "let's multiply the gallons".

Regarding the volume - do you know how to calculate the volume of a box? (rectangular prism) Can you represent the flooded basement using boxes?

eddy2017

Full Member
Yes, volume. Not sure what you mean by "multiplying the amount of gallons". Multiplying by what? Why? What's the _main_ formula? The 'top-down' approach I am pushing tells you to write down the main formula/relationship, then do what it tells you: if you know all variables, then evaluate or solve it. If some variables are not known, then find formulas/relationships for them. Never do random stuff such as "let's multiply the gallons".

Regarding the volume - do you know how to calculate the volume of a box? (rectangular prism) Can you represent the flooded basement using boxes?
volume of a box= l * w * h (height).
boxes?. well. i will give it a try. i will make two boxes of the whole basement and see what happens. give some time to draw them.

eddy2017

Full Member
i am gonna make two boxes or rectangles
let's say box A measures 40 ft by 25ft (length by width) [25 ft cos i am halving the 50 ft i have above]
the smaller rectangle or box B measures 16 ft (cos 24 ft + 16 t make up the 40 ft given) by 22ft which is the measure already given

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lev888

Senior Member
i am gonna make two boxes or rectangles
let's say box A measures 40 ft by 25ft (length by width) [25 ft cos i am halving the 50 ft i have above]
the smaller rectangle or box B measures 16 ft (cos 24 ft + 16 t make up the 40 ft given) by 22ft which is the measure already given
I agree with 16 by 22. The reasoning makes sense - 16 is what's left of 40 after you subtract 24. But why did you use completely different reasoning for 40 by 25?

eddy2017

Full Member
I agree with 16 by 22. The reasoning makes sense - 16 is what's left of 40 after you subtract 24. But why did you use completely different reasoning for 40 by 25?
40ft is the length already given.
25 ft width = half of 50ft which seems to me is the width of the whole basement
and the height, well, i think it should be the same 16 inches

lev888

Senior Member
40ft is the length already given.
25 ft width = half of 50ft which seems to me is the width of the whole basement
and the height, well, i think it should be the same 16 inches
You explained where 16 came from. You calculated it exactly. Why is it that for the first rectangle you think that it's enough to estimate the measurement? There is no "seems" in math. Please apply the same method as for the second rectangle.

eddy2017

Full Member
You explained where 16 came from. You calculated it exactly. Why is it that for the first rectangle you think that it's enough to estimate the measurement? There is no "seems" in math. Please apply the same method as for the second rectangle.
it is 16 inches cos that is the depth of the basement but I do not know how to represent it in the figure. i do not see it in the diagram for box A. i dont see it how i can calculate it. B was easy cos it was what was left of 24, that is ,16 which makes up 40ft the entire length.
But now i am stumped.

lev888

Senior Member
it is 16 inches cos that is the depth of the basement but I do not know how to represent it in the figure. i do not see it in the diagram for box A. i dont see it how i can calculate it. B was easy cos it was what was left of 24, that is ,16 which makes up 40ft the entire length.
But now i am stumped.
16 inches is the height of both boxes. I'm talking about the dimensions of the 2 rectangles. The second makes sense. The first doesn't. Please try again and use the same approach as for the second instead of "half of 50ft". Why half?

eddy2017

Full Member
16 inches is the height of both boxes. I'm talking about the dimensions of the 2 rectangles. The second makes sense. The first doesn't. Please try again and use the same approach as for the second instead of "half of 50ft". Why half?
oh oh I think I got it. HOW DUM CAN I GET?
i will minus 22 ft from 50 ft to find the width of Box A
50 -22 =28 ft
so, now
Box A: 40 ft by 28 ft
B:16 ft by 22 ft
area of Box A 1120 ft^2
area Box B 352 ft^2
i add the two areas now
1120+352=1472 ft^2
i multiply 1472 * 16 in to find the volume of the basement. I convert 16 inches to ft to work with like units
12 inch=1ft
so 16in=1ft4 in
1472ft^2* 1ft.4
=2060.8 ft^3
that is the volume of the basement 2060.8 ft^3
now i have to find how many gallons of water is that?
that is using the conversion measurement = 15415.8545
is it good so far?
now i will have to see how much time it will take to pump all this water at 50 gallons per minute.
please check all this first and tell me what you think.

lev888

Senior Member
oh oh I think I got it. HOW DUM CAN I GET?
i will minus 22 ft from 50 ft to find the width of Box A
50 -22 =28 ft
so, now
Box A: 40 ft by 28 ft
B:16 ft by 22 ft
area of Box A 1120 ft^2
area Box B 352 ft^2
i add the two areas now
1120+352=1472 ft^2
i multiply 1472 * 16 in to find the volume of the basement. I convert 16 inches to ft to work with like units
12 inch=1ft
so 16in=1ft4 in
1472ft^2* 1ft.4
=2060.8 ft^3
that is the volume of the basement 2060.8 ft^3
now i have to find how many gallons of water is that?
that is using the conversion measurement = 15415.8545
is it good so far?
now i will have to see how much time it will take to pump all this water at 50 gallons per minute.
please check all this first and tell me what you think.
Looks good until inches to feet conversion. What exactly is 1ft.4? 1.4ft? 4 inches is 0.4 feet? That would've been nice - easy to convert. This is not the case unfortunately.
Don't forget that there are 2 pumps.

eddy2017

Full Member
Looks good until inches to feet conversion. What exactly is 1ft.4? 1.4ft? 4 inches is 0.4 feet? That would've been nice - easy to convert. This is not the case unfortunately.
Don't forget that there are 2 pumps.
Youre right. 16 inches is not 1.4 ft
it is better to divide 16 ÷12= 1.33
1.33 ft