# A storage tank is in the form of a cube. When it is full of water, the volume of water is 15.625 m³. If the present depth of water is 1.3 m, find the volume of water already used from the tank.

**Solution:**

Given, storage tank is in the form of a cube

When the tank is full of water, the volume of water is 15.625 m³

The present depth of water is 1.3 m

We have to find the volume of water already used from the tank.

Let the side of the cube = x m

Volume of cube = a³

Where, a is the side of the cube

Given, a³ = 15.625

Taking cube root,

a = 2.5 m

Given, present depth of water = 1.3 m

Height of water being used = 2.5 - 1.3

= 1.2 m

Volume of water used = 1.2 × 2.5 × 2.5

= 7.5 m³

We know, 1 m³ = 1000 litres

So, volume of water used = 7.5 × 1000

= 7500 litres

Therefore, the volume of water already used in the tank is 7500 litres.

**✦ Try This: **A storage tank is in the form of a cube. When it is full of water, the volume of water is 9 m³. If the present depth of water is 2 m, find the volume of water already used from the tank.

**☛ Also Check: **NCERT Solutions for Class 9 Maths Chapter 13

**NCERT Exemplar Class 9 Maths Exercise 13.3 Problem 2**

## A storage tank is in the form of a cube. When it is full of water, the volume of water is 15.625 m³. If the present depth of water is 1.3 m, find the volume of water already used from the tank.

**Summary:**

A storage tank is in the form of a cube. When it is full of water, the volume of water is 15.625 m³. If the present depth of water is 1.3 m, the volume of water already used from the tank is 7500 litres

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