13 A traffic roundabout has a circular garden in the centre and two lanes for traffic
encircling the garden. The diameter of the
garden is 16 metres and each lane is 3 metres
wide. Each lane is to be resurfaced. Calculate
the area to be resurfaced. Answer in square
metres to the nearest whole number.

Step-by-step explanation:

The area to be resurfaced is the area of the

whole circle including garden and lanes minus  

the area of the garden.

Area of a circle is (pi)r2

radius of garden is (1/2)diameter = 8 m

Garden area:  (pi)82 = 64(pi) m2

Diameter of garden plus traffic lanes is

16 + 2(6) because we add 6 m to both sides

of the diameter of the garden.

Full diameter = 16+12 = 28 m

Full radius = 28/2 = 14 m

Full area:  (pi)142 = 196(pi) m2

Area to be resurfaced:

196(pi) - 64(pi) = 132(pi) m2  ≅ 415 m2