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

To calculate the volume of one concrete block, we use the formula:

$$ext{Volume} = ext{side} imes ext{side} imes ext{height}$$

The side length of the concrete block is 0.5 m (or 50 cm) and the height is 0.18 m (or 180 mm). Therefore:

$$ext{Volume} = 0.5 imes 0.5 imes 0.18 = 0.045 ext{ m}^3$$

Using the area formula:

$$ext{Area} = ext{side} imes ext{side}$$

For one block:

$$ext{Area} = 0.5 imes 0.5 = 0.25 ext{ m}^2$$

For 12 blocks:

$$ext{Total Area} = 12 imes 0.25 = 3 ext{ m}^2$$

To find the area of the walkway, we apply the formula:

$$ext{Area} = ext{length} imes ext{breadth}$$

Substituting the dimensions:

$$ext{Area} = 4.05 imes 1.45 = 5.8725 ext{ m}^2$$

Next, subtract the area occupied by 12 blocks:

Total area of blocks is 3 m².

Thus, area to be covered with pebbles:

$$ext{Area} = 5.8725 - 3 = 2.8725 ext{ m}^2$$

The total required area is 5.7 m² and each bag covers 0.36 m². The number of bags needed is calculated by:

ext{Number of bags} = rac{5.7}{0.36} ext{ bags}

Calculating this gives:

$$ext{Number of bags} ext{ } oughly 15.83 ext{ bags}$$

Thus, rounding up, Thabiso needs 16 bags of pebbles.