Water tank volume problems
A rectangular water tank, fish tank or farm trough is part full of water, and its length and width are given. Some water is poured in or let out, and it ends up a different fraction full. The student finds how many litres the full tank holds, then a length: the tank's height, or how deep the water was at the start or is at the end.
The key is that the change in the fraction is the water that moved: if 3/4 − 2/5 = 7/20 of the tank is the litres poured in, one twentieth and then the whole tank follow. The height then needs litres turned into cubic centimetres (1 litre is 1,000 cm³) and divided by the area of the base, which is where most slips happen. The step-by-step working draws each stage on the tank.
Numbers&Me is free. Sign up to practise more, or set it as homework in under a minute, and it marks itself.
What changes each time
- Water poured in or let out, with levels in halves, thirds, quarters, fifths, sixths, eighths or tenths, sometimes starting or ending full
- Tanks 40 to 240 cm long and 25 to 100 cm wide, holding from 25 to 1,800 litres, always a whole number of litres
- The second answer: the tank's height, or the depth of the water before or after
More area, perimeter and volume practice
- Area by counting squares (Grade 2)
- Area and perimeter of a square (Grade 3)
- Area and perimeter of a rectangle (Grade 3)
- Area with half squares (Grade 3)
- Area of an L-shape (Grade 3)
- Perimeter of an L-shape (Grade 3)
- Draw a rectangle with a given area and perimeter (Grade 3)
- Missing side of a rectangle (Grade 4)
- Rectangle sides from a ratio (Grade 4)
- Area of a right triangle (Grade 4)
- Area of an isosceles triangle (Grade 4)
- Area of a scalene triangle (Grade 4)
- Area of an irregular polygon (Grade 5)
- Missing triangle in a square (Grade 5)
- Volume by counting cubes (Grade 5)