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One pipe can fill a pool 1.25 times faster than a second [#permalink]

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26 Jan 2014, 15:48

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One pipe can fill a pool 1.25 times faster than a second pipe. When both pipes are opened, they fill the pool in five hours. How long would it take to fill the pool if only the slower pipe is used?

A. 11.25 B. 11.52 C. 1.25 D. 9 E. 7.2

I would appreciate if someone can explain me this using the Rate Time Work chart (as used by Manhattan). That will help me understand better and easier.

One pipe can fill a pool 1.25 times faster than a second pipe. When both pipes are opened, they fill the pool in five hours. How long would it take to fill the pool if only the slower pipe is used?

A. 11.25 B. 11.52 C. 1.25 D. 9 E. 7.2

I would appreciate if someone can explain me this using the Rate Time Work chart (as used by Manhattan). That will help me understand better and easier.

Thank you!

Say the rate of the slower pipe is R pool/hour, then the rate of the faster pipe would be 1.25R=5R/4. Since when both pipes are opened, they fill the pool in five hours, then their combined rate is 1/5 pool/hour.

Thus we have that R + 5R/4 = 1/5 --> R = 4/45 pool/hour --> time is reciprocal of rate thus it's 45/4 =11.25 hours.

Re: One pipe can fill a pool 1.25 times faster than a second [#permalink]

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12 Feb 2014, 09:34

flower07 wrote:

One pipe can fill a pool 1.25 times faster than a second pipe. When both pipes are opened, they fill the pool in five hours. How long would it take to fill the pool if only the slower pipe is used?

A. 11.25 B. 11.52 C. 1.25 D. 9 E. 7.2

I would appreciate if someone can explain me this using the Rate Time Work chart (as used by Manhattan). That will help me understand better and easier.

Thank you!

Hi Trying to solve the way you want From the table you can find the rate,R, of smaller pipe. Then time is inverse of rate so answer would be A...

Re: One pipe can fill a pool 1.25 times faster than a second [#permalink]

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27 Jul 2014, 00:39

entire job is done in 5 hours, hence 20% of the job is done per hour. slower one does 8.88% and faster one does 11.12% of it. so the slower pipe completes the task in 100/8.88 = 11.25 hours

Re: One pipe can fill a pool 1.25 times faster than a second [#permalink]

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15 Sep 2014, 07:13

1

This post received KUDOS

flower07 wrote:

One pipe can fill a pool 1.25 times faster than a second pipe. When both pipes are opened, they fill the pool in five hours. How long would it take to fill the pool if only the slower pipe is used?

A. 11.25 B. 11.52 C. 1.25 D. 9 E. 7.2

I would appreciate if someone can explain me this using the Rate Time Work chart (as used by Manhattan). That will help me understand better and easier.

Thank you!

Let me give you an elaborate explanation on how you can use this (I have also used MGMAT's way of approaching the problems, but adopted according to the time needs)

Let's assume the rate of the slower pipe is: x So, the rate of the faster pipe would be: 1.25x Working together, their rate will be x + 1.25x = 2.25x

As the question says, they take 5 hours to fill up the tank working together, so:

Rate x Time = Work 2.25x x 5 = 1 2.25x = 1/5 x = 1/5 / 2.25 = 4/45

So, the rate of the slower pipe, x = 4/45

Now, let's see how long it takes for the slower pipe to complete the task:

Rate x Time = Work 4/45 x Time = 1 Time = 1 / 4/45 = 45/4 = 11.25

Re: One pipe can fill a pool 1.25 times faster than a second [#permalink]

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15 Sep 2014, 07:14

1

This post was BOOKMARKED

flower07 wrote:

One pipe can fill a pool 1.25 times faster than a second pipe. When both pipes are opened, they fill the pool in five hours. How long would it take to fill the pool if only the slower pipe is used?

A. 11.25 B. 11.52 C. 1.25 D. 9 E. 7.2

I would appreciate if someone can explain me this using the Rate Time Work chart (as used by Manhattan). That will help me understand better and easier.

Thank you!

Let me give you an elaborate explanation on how you can use this (I have also used MGMAT's way of approaching the problems, but adopted according to the time needs)

Let's assume the rate of the slower pipe is: x So, the rate of the faster pipe would be: 1.25x Working together, their rate will be x + 1.25x = 2.25x

As the question says, they take 5 hours to fill up the tank working together, so:

Rate x Time = Work 2.25x x 5 = 1 2.25x = 1/5 x = 1/5 / 2.25 = 4/45

So, the rate of the slower pipe, x = 4/45

Now, let's see how long it takes for the slower pipe to complete the task:

Rate x Time = Work 4/45 x Time = 1 Time = 1 / 4/45 = 45/4 = 11.25

Re: One pipe can fill a pool 1.25 times faster than a second [#permalink]

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28 Jan 2017, 00:21

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One pipe can fill a pool 1.25 times faster than a second [#permalink]

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28 Jan 2017, 11:39

One pipe can fill a pool 1.25 times faster than a second pipe. When both pipes are opened, they fill the pool in five hours. How long would it take to fill the pool if only the slower pipe is used?

A. 11.25 B. 11.52 C. 1.25 D. 9 E. 7.2

combined rate=r+(5r/4)=9r/4 total work=(9r/4)*5=45r/4 (45r/4)/r=11.25 hours for slower pipe to complete work alone A