Algebra : Applied Problem

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anirudhbhalotia: Master | Next Rank: 500 Posts; Posts: 123; Joined: Tue Nov 23, 2010 7:18 pmFollowed by: 4 members; Location: Mumbai, India; Thanked: 5 times

by anirudhbhalotia » Thu Jan 13, 2011 10:18 pm

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An empty pool being filled with water at a constant rate takes 8 hrs to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?

A. 5 hr 30 min
B. 5 hr 20 min
C. 4 hr 48 min
D. 3 hr 12 min
E. 2 hr 40 min

[spoiler]OA - B(can some one explain)[/spoiler]

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Source: Beat The GMAT — Problem Solving | Thu Jan 13, 2011 10:18 pm

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Anurag@Gurome: GMAT Instructor; Posts: 3835; Joined: Fri Apr 02, 2010 10:00 pmFollowed by: 523 members; Location: Milpitas, CA; Thanked: 1854 times; GMAT Score:770

by Anurag@Gurome » Thu Jan 13, 2011 10:51 pm

anirudhbhalotia wrote:An empty pool being filled with water at a constant rate takes 8 hrs to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?

A. 5 hr 30 min
B. 5 hr 20 min
C. 4 hr 48 min
D. 3 hr 12 min
E. 2 hr 40 min

The tank is already fill to (3/5) of its capacity.
Therefore, empty space in the tank = (1- 3/5) = (2/5) of its capacity.

Now, to fill to (3/5) of its capacity time required = 8 hrs
Thus, to fill to (2/5) of its capacity time required = [8*(2/5)]/(3/5) = (8*2)/3 hrs = (5 + 1/3) hrs = 5 hrs 20 minutes

The correct answer is B.

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towerSpider: Master | Next Rank: 500 Posts; Posts: 155; Joined: Mon Dec 13, 2010 11:02 am; Thanked: 3 times

by towerSpider » Thu Jan 13, 2011 10:55 pm

anirudhbhalotia wrote:An empty pool being filled with water at a constant rate takes 8 hrs to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?

A. 5 hr 30 min
B. 5 hr 20 min
C. 4 hr 48 min
D. 3 hr 12 min
E. 2 hr 40 min

[spoiler]OA - B(can some one explain)[/spoiler]

X3/5=8 (X is time taken for full capacity)
X=40/3

40/3 * 2/5 = 80/15 = 5 hrs, 20 min

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anirudhbhalotia: Master | Next Rank: 500 Posts; Posts: 123; Joined: Tue Nov 23, 2010 7:18 pmFollowed by: 4 members; Location: Mumbai, India; Thanked: 5 times

by anirudhbhalotia » Sun Jan 16, 2011 2:29 am

Not getting the logic.

Lets say the capacity is 100.

So it takes 8 hrs to fill, 3/5 of 100...which is 60.

How long will it take to fill remaining 40?

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Anurag@Gurome: GMAT Instructor; Posts: 3835; Joined: Fri Apr 02, 2010 10:00 pmFollowed by: 523 members; Location: Milpitas, CA; Thanked: 1854 times; GMAT Score:770

by Anurag@Gurome » Sun Jan 16, 2011 2:32 am

anirudhbhalotia wrote:Lets say the capacity is 100.

So it takes 8 hrs to fill, 3/5 of 100...which is 60.

How long will it take to fill remaining 40?

To fill 60 it takes 8 hrs
To fill 1 it will take (8/60) hrs
To fill 40 it will take (8*40)/60 hrs

(8*40)/60 hrs = (16/3) hrs = (5 + 1/3) hrs = 5 hrs + (1/3) hrs = 5rs + 20 minutes = 5 hrs 20 minutes

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anirudhbhalotia: Master | Next Rank: 500 Posts; Posts: 123; Joined: Tue Nov 23, 2010 7:18 pmFollowed by: 4 members; Location: Mumbai, India; Thanked: 5 times

by anirudhbhalotia » Sun Jan 16, 2011 2:37 am

Anurag@Gurome wrote:
anirudhbhalotia wrote:Lets say the capacity is 100.

So it takes 8 hrs to fill, 3/5 of 100...which is 60.

How long will it take to fill remaining 40?
To fill 60 it takes 8 hrs
To fill 1 it will take (8/60) hrs
To fill 40 it will take (8*40)/60 hrs

(8*40)/60 hrs = (16/3) hrs = (5 + 1/3) hrs = 5 hrs + (1/3) hrs = 5rs + 20 minutes = 5 hrs 20 minutes

Gotcha!

This is what I was trying to do...but was trying to do in terms of hours and not how much to fill.

Thanks Anurag!

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GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members; Location: New York, NY; Thanked: 13060 times; GMAT Score:790

by GMATGuruNY » Sun Jan 16, 2011 3:58 am

anirudhbhalotia wrote:An empty pool being filled with water at a constant rate takes 8 hrs to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?

A. 5 hr 30 min
B. 5 hr 20 min
C. 4 hr 48 min
D. 3 hr 12 min
E. 2 hr 40 min

[spoiler]OA - B(can some one explain)[/spoiler]

We can plug in a value for the pool.

Let pool = 40 liters.
Work completed in 8 hours = (3/5)*40 = 24 liters.
Thus, rate = w/t = 24/8 = 3 liters per hour.
Work remaining = 40-24 = 16 liters.
Time to finish = w/r = 16/3 = 5 hours, 20 min.

The correct answer is B.

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Jeff@TargetTestPrep: GMAT Instructor; Posts: 1462; Joined: Thu Apr 09, 2015 9:34 amFollowed by: 22 members; Location: New York, NY; Thanked: 39 times

hi

by Jeff@TargetTestPrep » Thu Jun 28, 2018 5:14 pm

anirudhbhalotia wrote:An empty pool being filled with water at a constant rate takes 8 hrs to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?

A. 5 hr 30 min
B. 5 hr 20 min
C. 4 hr 48 min
D. 3 hr 12 min
E. 2 hr 40 min

We need to find the time to fill the remaining 2/5 of the pool. Thus, we can use the following proportion:

8/(3/5) = x/(2/5)

40/3 = 5x/2

15x = 80

x = 80/15 = 16/3 = 5 1/3 hr = 5 hr 20 min

Alternate Solution:

Let's assume the capacity of the pool is 5 gallons. Since it takes 8 hours to fill 3/5 x 5 = 3 gallons, the pool is filled at a rate of 3/8 gallons per hour. Since 3 gallons of the pool is already filled, the remaining 5 - 3 = 2 gallons will be filled in 2 x (8/3) = 16/3 = 5 1/3 hours; or 5 hours and 20 minutes.

Answer: B

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Fri Jun 29, 2018 5:08 am

An empty pool being filled with water at a constant rate take 8 hours to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool ?

A. 5hr 30 min
B. 5hr 20 min
C. 4hr 48 min
D. 3hr 12 min
E. 2hr 40 min

We know it takes 8 hours to fill to 3/5 of its capacity.
We want to know how long it will take to fill the remaining 2/5 of capacity.

IMPORTANT: 2/5 is 2/3 as big as 3/5
So, if it takes 8 hours to fill 3/5 of the pool, then the time to fill 2/5 of the pool = (2/3)(8) hours = 16/3 hours = 5 1/3 hours = [spoiler]5 hours and 20 minutes = B[/spoiler]

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Fri Jun 29, 2018 5:09 am

anirudhbhalotia wrote:An empty pool being filled with water at a constant rate takes 8 hrs to fill to 3/5 of its capacity. How much more time will it take to finish filling the pool?

A. 5 hr 30 min
B. 5 hr 20 min
C. 4 hr 48 min
D. 3 hr 12 min
E. 2 hr 40 min

[spoiler]OA - B(can some one explain)[/spoiler]

Here's a slightly different approach.

It takes 8 hours to fill to 3/5 of its capacity.
So, in 1/3 the time, we'll fill 1/3 as much. In other words, in 8/3 hours we can fill 1/5 of the pool.

We want to know how long it will take to fill 2/5 of the pool.
So, it will take twice as long as 8/3 hours.
This means that, the time to fill 2/5 of the pool = 2(8/3)
= 16/3 hours
= 5 1/3 hours
= 5 hours and 20 minutes
= B

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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