You are filling a right cylinder tank with colored sand. how much sand in cubic inches must you add to the tank with a radius of 20 inches and height of 5 inches, in order to fill the tank 4 /7 full?

The volume for a right cylinder is V = pi r^2 h.  If you are filling a 5 inch high tank 4/7 of the way full, you are filling it to a height of 20/7 inches.  Using the formula, V = pi (20)^2 (20/7).  Leaving that volume in terms of pi you get a volume of 1142.86pi inches cubed.  If you're not leaving it in terms of pi, multiply the pi in.