African Concrete Blocks is a company that manufactures square concrete blocks - NSC Mathematical Literacy - Question 3 - 2019 - Paper 1

The dimensions of the concrete block are given as follows:

• Side length = 0.5 m (or 50 cm)
• Height = 0.18 m (or 180 mm)

Using the formula for volume:

$$Volume = \text{side} \times \text{side} \times \text{height}\ Volume = 0.5 \text{ m} \times 0.5 \text{ m} \times 0.18 \text{ m} = 0.045 \text{ m}^3$$

Using the side length of one block (0.5 m), we can calculate the area of one block:

$$Area = \text{side} \times \text{side} = 0.5 \text{ m} \times 0.5 \text{ m} = 0.25 \text{ m}^2$$

Total area for 12 blocks:

$$Total \ area = 12 \times 0.25 \text{ m}^2 = 3 \text{ m}^2$$

The dimensions of the walkway are:

• Length = 4.05 m
• Breath = 1.45 m

Using the area formula:

$$Area = \text{length} \times \text{breath} = 4.05 \text{ m} \times 1.45 \text{ m} = 5.8725 \text{ m}^2$$

Now, we need to subtract the area occupied by the concrete blocks:

$$Area \ to \ be \ covered = 5.8725 \text{ m}^2 - 3 \text{ m}^2 = 2.8725 \text{ m}^2$$

Given the area needed for pebbles:

• Area = 5.7 m²

If one bag covers 0.36 m², we calculate:

$$\text{Number of bags} = \frac{5.7 \text{ m}^2}{0.36 \text{ m}^2} \approx 15.83 \text{ bags}$$

Since we cannot have a fraction of a bag, we round up to 16 bags.