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When a cylindrical tank is filled with water

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When a cylindrical tank is filled with water

by BTGmoderatorDC » Tue Dec 12, 2017 4:35 am
When a cylindrical tank is filled with water at a rate of 22 cubic meters per hour, the level of water in the tank rises at a rate of 0.7 meters per hour. Which of the following best approximates the radius of the tank in meters?

A. √10/2
B. √10
C. 4
D. 5
E. 10

Can some experts give a simple solution in this problem?

OA B
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by GMATGuruNY » Tue Dec 12, 2017 5:03 am
lheiannie07 wrote:When a cylindrical tank is filled with water at a rate of 22 cubic meters per hour, the level of water in the tank rises at a rate of 0.7 meters per hour. Which of the following best approximates the radius of the tank in meters?

A. √10/2
B. √10
C. 4
D. 5
E. 10
π ≈ 22/7.

After 1 hour, the volume in the tank = 22 cubic meters, with a height of 0.7 meters.
Since V = πr²h, we get:
22 = π(r²)(0.7)
22 = (22/7)(r²)(7/10)
1 = r²/10
10 = r²
√10 = r.

The correct answer is B.
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by GMATWisdom » Tue Dec 12, 2017 5:18 am
lheiannie07 wrote:When a cylindrical tank is filled with water at a rate of 22 cubic meters per hour, the level of water in the tank rises at a rate of 0.7 meters per hour. Which of the following best approximates the radius of the tank in meters?

A. √10/2
B. √10
C. 4
D. 5
E. 10

Can some experts give a simple solution in this problem?

OA B
if r is the radius of the cylinder then it would get filled @ (Ï€r^2 )*0.7
Therefore (Ï€r^2 )*0.7=22
Put the value of π as 22/7 and you get
[(22/7)r^2 ]*0.7= 22
Solving this you get r^2=7/0.7=10
Or r=√10
Hence B is the correct option
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