A rectangular water tank measures 15 m × 6 m at the top and is 10 m deep. It is currently full of water. If the water level is lowered by 1 m due to water being drawn out, how much water remains in the tank?

Given: The length, breadth and depth of the rectangular water tank are 15 m, 6 m and 10 m, respectively.

If the water level lowers by 1 m, then the depth of the remaining water level is 9 m.

Using the formula of volume of a cuboid, V = l × b × h

⇒ V = 15 × 6 × 9

⇒ V = 810 cubic metre

We know that:

1 cubic metre = 1000 liters

So, 810 cubic metres = 810 × 1000

= 810000 litres

Therefore, the water left in the water tank is 810,000 litres.