Question

William has a 26 -liter glass tank. First, he wants to put some marbles in it, all of the same volume. Then, he wants to fill the tank with water until it's completely full. If he uses 85 marbles, he will have to add 20.9 liters of water.
What is the volume of each marble?

How much water is necessary if William uses 200 marbles?

Answer 1

Subtract the volume of the water from the volume of the tank to get the total volume of the marbles.

26 liters - 20.9 liters = 5.1 liters

He has 20.9 liters of water.

He has 85 marbles that add up to 5.1 liters of volume.

To find the volume of one marble, we divide 5.1 liters by 85.

(5.1 liters)/85 = 0.06 liters

The volume of each marble is 0.06 liters.

If he uses 200 marbles, the the marbles will occupy 200 * 0.06 liters = 12 liters.

The volume of the tank is 26 liters. 12 liters of volume is occupied by the marbles. The rest of the volume is water.

26 liters - 12 liters = 14 liters