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# desert outpost has a water supply that is sufficient

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Joined: 07 Jun 2014
Posts: 4710
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
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desert outpost has a water supply that is sufficient [#permalink]  18 Jan 2016, 02:29
Expert's post
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Question Stats:

100% (01:42) correct 0% (00:00) wrong based on 9 sessions
A desert outpost has a water supply that is sufficient to last 21 days for 15 people. At the same average rate of water consumption per person, how many
days would the water supply last for 9 people?

A 28.0
B 32.5
C 35.0
D 37.5
E 42.0

Practice Questions
Question: 25
Page: 336
Difficulty: medium
[Reveal] Spoiler: OA

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Sandy
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GMAT Club Legend
Joined: 07 Jun 2014
Posts: 4710
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 91

Kudos [?]: 1612 [1] , given: 375

Re: desert outpost has a water supply that is sufficient [#permalink]  18 Jan 2016, 04:54
1
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Expert's post
Solution

The water supply is enough for 15 people to survive 21 days. Assuming the same average rate of water consumption per person, 1 person would have enough
water to last for (15)(21)=315 days. Therefore, 9 people would have enough water for $$\frac{1}{9}$$ of the 315 days, or 35 days. The correct answer is Choice C.
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Re: desert outpost has a water supply that is sufficient [#permalink]  17 May 2018, 05:56
Expert's post
sandy wrote:
A desert outpost has a water supply that is sufficient to last 21 days for 15 people. At the same average rate of water consumption per person, how many
days would the water supply last for 9 people?

A 28.0
B 32.5
C 35.0
D 37.5
E 42.0

Let's assign a "nice value" to the amount of water that's available.
Let's first day that each person drinks 1 liter of water EACH DAY.
At that rate, the 15 people would drink a total of 15 liters EACH DAY.
So, in 21 days, they'd drink a total of 315 liters [since (15)(21) = 315].

Now let's see how long that 315 liters of water will last if there are only 9 people.
If each person drinks 1 liter of water EACH DAY, then the 9 people would drink a total of 9 liters EACH DAY.
So, the number of days it takes to drink all 315 = 315/9 = 35

Cheers,
Brent
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Brent Hanneson – Creator of greenlighttestprep.com

Re: desert outpost has a water supply that is sufficient   [#permalink] 17 May 2018, 05:56
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