Question

The circular face of a watch has an area that measures between 800 and 900 square millimeters.

What could be the radius of the watch face? Use 3.14 for Pi.

14 mm
15 mm
16 mm
17 mm

Answer 1

Area = πr^2 with π = 3.14.

- r = 14: A = 3.14×196 = 615.44 (too small)
- r = 15: A = 3.14×225 = 706.50 (too small)
- r = 16: A = 3.14×256 = 803.84 (between 800 and 900)
- r = 17: A = 3.14×289 = 907.46 (too large)

So the radius could be 16 mm.