Question

A Hydrogenator water gun has a cylindrical water tank, which is 30 centimeters long. Using a hose, Jack fills his Hydrogenator with 7T cubic centimeters of his water tank every second. If it takes him 8 minutes to fill the tank with water, what is the diameter of the circular base of the gun's water tank?

• A. $4$ cm
• B. $10$ cm
• C. $8$ cm
• D. $6$ cm

Answer 1

Answer: (C)

$8$ cm

8 cm: In 8 minutes, or 480 seconds, $480\pi c{m}^3$ of water flows into the tank. Therefore, the volume of the tank is 480n. You are given a height of 30, so you can solve for the radius:
$v=\pi r^2\times h$
$480\pi =30\pi r^2$
$r^2=16$
$r=4$
Therefore, the diameter of the tank's base is 8 centimeters.