PSLE
The figure shows a rectangular grass patch and an L-shaped footpath. The width of the footpath is 20 cm. The footpath is tiled using 52 circular tiles of diameter 10 cm, following the pattern shown. Each tile is in contact with those next to it.

1. What is the area of the footpath not covered by the tiles? Take π = 3.14.
2. What is the perimeter of the grass patch?

(a)
Area of a circular tile
= 3.14 x 5 x 5
= 78.5 cm²

Area of a square plot that is under a circular tile
= 10 x 10
= 100 cm²

Area of the footpath not covered by a circular tile
= 100 - 78.5
= 21.5 cm²

Area of the footpath not covered by all the tiles
= 21.5 x 52
= 1118 cm²

(b)
Number of circular tiles touching the 2 lengths of the grass patch
= (52 - 4) ÷ 2
= 48 ÷ 2
= 24

Perimeter of the grass patch
= 2 x 24 x 10
= 480 cm

Answer(s): (a) 1118 cm²; (b) 480 cm