BTGmoderatorDC 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
OA B
Source: Manhattan Prep
Let's examine what occurs in a
1-hour period
The volume of water increases by 22 cubic meters.
The height of the water increases by 0.7 meters.
So, we need to find the radius of a 0.7 meter high cylinder that has a volume of 22 cubic meters.
Volume = πr²h
22 = πr²(0.7)
IMPORTANT: notice that (Ï€)(0.7) = approximately 2.2
So, we get: 22 = (2.2)r²
Divide both sides by 2.2: 10 = r²
Solve: r = √10 (approximately)
Answer: B
Cheers,
Brent
