What mass of water in grams will fill a fish tank 100 cm long, 50 cm wide, and 30 cm high?

150,000cm^3, or 1,500m^3

Explanation:

The question is basically asking the volume of this rectangular tank.

The formula to find the volume is length x width x height.

This is because we're trying to find the area of the base (length x width), and then we're multiplying the base times the height, to get how much of the base area can fit in the height of the rectangle.

So, the answer is 100cm x 50cm x 30cm = 150,000cm^3, or 1,500m^3, because 1 meter = 100 centimeters.