Question

The diameter of a circle is 7 cm. Its circumference is
(a) 44 cm
(b) 22 cm
(c) 28 cm
(d) 14 cm

Answer 1

(b) 22 cm
$$\begin{gathered} \mathrm{Radius}=\frac{\mathrm{Diameter}}{2}=\frac{7}{2}\mathrm{cm} \\ \mathrm{Circumference}\mathrm{of}\mathrm{the}\mathrm{circle}=2\pi r=(2\times \frac{22}{7}\times \frac{7}{2})\mathrm{cm} \\ =22\mathrm{cm} \end{gathered}$$