Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 04 May 2015, 18:32

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# The concentration of a certain chemical in a full water tank

Author Message
TAGS:
Intern
Joined: 13 Sep 2006
Posts: 6
Followers: 0

Kudos [?]: 0 [0], given: 0

The concentration of a certain chemical in a full water tank [#permalink]  18 Sep 2006, 12:44
The concentration of a certain chemical in a full water tank depends on the depth of the water. At a depth that is x feer below the top of the tank, the concentration is 3+(4/sq rt of 5-x) parts per million, where 0<x<4. To the nearest 0.1 ft, at what depth is the concentration equal to 6 parts per million?

Is substituting the answer choices the best way to solve this?

A) 2.4 ft
B) 2.5 ft
C) 2.8 ft
D) 3.0 ft
E) 3.2 ft

Is this considered a difficult question?
Intern
Joined: 17 Sep 2006
Posts: 45
Location: China
Followers: 0

Kudos [?]: 1 [0], given: 0

Re: Word Problem [#permalink]  18 Sep 2006, 14:52
rfrcuhetr1 wrote:
The concentration of a certain chemical in a full water tank depends on the depth of the water. At a depth that is x feer below the top of the tank, the concentration is 3+(4/sq rt of 5-x) parts per million, where 0<x<4. To the nearest 0.1 ft, at what depth is the concentration equal to 6 parts per million?

Is substituting the answer choices the best way to solve this?

A) 2.4 ft
B) 2.5 ft
C) 2.8 ft
D) 3.0 ft
E) 3.2 ft

Is this considered a difficult question?

I don't understand the red part of the problem
Senior Manager
Joined: 31 Jul 2006
Posts: 440
Followers: 3

Kudos [?]: 14 [0], given: 0

Re: Word Problem [#permalink]  18 Sep 2006, 17:03
Iawfy wrote:

I don't understand the red part of the problem

3 + 4/sqrt(5-x) I'm guessing
Senior Manager
Joined: 28 Aug 2006
Posts: 302
Followers: 10

Kudos [?]: 96 [0], given: 0

Re: Word Problem [#permalink]  18 Sep 2006, 17:50
rfrcuhetr1 wrote:
The concentration of a certain chemical in a full water tank depends on the depth of the water. At a depth that is x feer below the top of the tank, the concentration is 3+(4/sq rt of 5-x) parts per million, where 0<x<4. To the nearest 0.1 ft, at what depth is the concentration equal to 6 parts per million?

Is substituting the answer choices the best way to solve this?

A) 2.4 ft
B) 2.5 ft
C) 2.8 ft
D) 3.0 ft
E) 3.2 ft

Is this considered a difficult question?

this is quite simple.

3+(4/sqrt(5-x) = 6
4/sqrt(5-x)=3
sqrt(5-x)=4/3
5-x=9/16
x=3.2

So E
_________________

Last edited by cicerone on 24 Sep 2008, 23:59, edited 1 time in total.
Intern
Joined: 16 Aug 2006
Posts: 17
Followers: 0

Kudos [?]: 0 [0], given: 0

rfrcuhetr1, you could also plug in and get to an answer relatively fast. of all the answers which one is the easiest to plug in into the equation? it's D, 3.0. so,

3 + (4/sqrt(5-3)) = 3 + 4/sqrt(2) = 3 + 2*sqrt(2) = 3 + sqrt(8).

since sqrt(9) is 3, sqrt (8) has to be < 3, so 3 +sqrt(8) is less than 6.

so that eliminates A through D and you are left with E.
Similar topics Replies Last post
Similar
Topics:
2 The concentration of a certain chemical in a full water tank 4 23 Jun 2009, 04:01
The concentration of a certain chemical in a full water tank 2 20 Aug 2008, 01:15
A certain tank is exactly one quarter full of water. At noon 3 21 Mar 2008, 05:13
The concentration of a certain chemical in a full water tank 2 21 Mar 2006, 21:40
2 The concentration of a certain chemical in a full water tank 9 16 Nov 2005, 17:58
Display posts from previous: Sort by