Answer:
300 Bags
Step-by-step explanation:
According to the Question,
The radius of the pool = 3.5 m; the overall radius including the border = 3.5 + 2 = 5.5m
overall area - pool area = border area(A)
A = π×5.5² - π×3.5²
A = 56.55 sq m
the volume of the concrete, change 50 mm to .05 m
56.55 * 05 = 2.8275 cu/meters
1 cubic metre requires 106 x 20 kg bags.
106 * 2.8275 = 299.715 ≈ 300bags