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, point, 9 liters of water.
What is the volume of each marble?

How much water is necessary if William uses 200 marbles?

Answer 1

You might think that the volume of a circle is needed to solve this problem but you can do it in a more simplified manner. First figure out how much water 85 marbles displace.

26-20.9=5.1 liters of water

Now, let us see how much water 200 marbles displace.

85 marble x (200/85) = 5.1 liters x (200/85)

200 marbles = 12 liters

We can find the amount of water needed to fill the tank now.

26-12=14 liters of water

answer: 14 liters of water