A wall of dimensions `24 m xx 5 m xx 0.25 m` is to be constructed using bricks of dimensions `25 cm xx 12.5 cm xx 7.5 cm`. Find the number of bricks requires if 5% of the wall is occupied by cement and mixture.

Answer

To solve the problem step by step, we will follow these steps:

### Step 1: Calculate the Volume of the Wall
The dimensions of the wall are given as \(24 \, m \times 5 \, m \times 0.25 \, m\).

\[ \text{Volume of the wall} = \text{length} \times \text{height} \times \text{thickness} = 24 \times 5 \times 0.25 \]

Calculating this:

\[ \text{Volume of the wall} = 24 \times 5 = 120 \, m^2 \]
\[ \text{Volume of the wall} = 120 \times 0.25 = 30 \, m^3 \]

### Step 2: Calculate the Volume of One Brick
The dimensions of one brick are given as \(25 \, cm \times 12.5 \, cm \times 7.5 \, cm\). We need to convert these dimensions into meters:

\[ 25 \, cm = \frac{25}{100} = 0.25 \, m \]
\[ 12.5 \, cm = \frac{12.5}{100} = 0.125 \, m \]
\[ 7.5 \, cm = \frac{7.5}{100} = 0.075 \, m \]

Now, we can calculate the volume of one brick:

\[ \text{Volume of one brick} = 0.25 \times 0.125 \times 0.075 \]

Calculating this:

\[ \text{Volume of one brick} = 0.25 \times 0.125 = 0.03125 \]
\[ \text{Volume of one brick} = 0.03125 \times 0.075 = 0.00234375 \, m^3 \]

### Step 3: Calculate the Volume of the Wall Occupied by Bricks
Since 5% of the wall is occupied by cement and mixture, 95% of the wall will be occupied by bricks.

\[ \text{Volume occupied by bricks} = 95\% \text{ of Volume of the wall} = 0.95 \times 30 \, m^3 \]

Calculating this:

\[ \text{Volume occupied by bricks} = 0.95 \times 30 = 28.5 \, m^3 \]

### Step 4: Calculate the Number of Bricks Required
Now, we can find the number of bricks required by dividing the volume occupied by bricks by the volume of one brick.

\[ \text{Number of bricks} = \frac{\text{Volume occupied by bricks}}{\text{Volume of one brick}} = \frac{28.5}{0.00234375} \]

Calculating this:

\[ \text{Number of bricks} = \frac{28.5}{0.00234375} = 12160 \]

### Final Answer
The number of bricks required to construct the wall is **12,160 bricks**.

---