radius water tank

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radius water tank

by canuckclint » Tue Nov 04, 2008 9:10 pm
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?

sqrt(10)/2
sqrt(10)
4
5
10
Source: — Problem Solving |

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by raunekk » Tue Nov 04, 2008 10:23 pm
imo:B

rate = 22 m^3 / hr = volume after one hour

level of water per hour= 0.7 m/hr = height after one hour

volume= pi * r^2 * h

22 = pi * r ^2 * 0.7

22/7 * 10 = pi * r^2

(pi = 22/7 )

thus, r ^2 = 10
r = sqroot 10

thx