Pisces is replacing paving stones for her inground pool. Her pool is 10m by 5m and is surrounded by a 1 1/2 border of paving stone. If each paving stone was 25 cm by 40 cm, in theory, how many paving stones will she need?

The number of paving stones she needs is 540 paving stone

Step-by-step explanation:

The given dimensions of Pisces' inground pool = 10 m by 5 m

The thickness of the border surrounding the pool = 1 1/2

The dimensions of each paving stone = 25 cm by 40 cm = 0.25 m by 0.4 m

The length dimension of the pool and border = 10 + 2 × 1 1/2 = 13 m

The width dimension of the pool = 5 + 2 × 1 1/2 = 8 m

The total area of the paving stone, = Area of pool + border - Area of pool

∴ = 13 m × 8 m - 10 m × 5 m = 54 m²

The total area of the paving stone = 54 m²

The area of each paving stone, = 0.25 m × 0.4 m = 0.1 m²/paving stone

The number of paving stones she needs, n = (The total area of the paving stone)/(The area of each paving stone)

∴ n = 54 m²/(0.1 m²/paving stone) = 540 paving stone.