question_answer

A circular road runs around a circular ground. If the difference between the circumferences of the outer circle and the inner Circle is 66 metres, the width of the road is: \[\left( Take\,\pi =\frac{22}{7} \right)\]

A)  21 metres         

B)  10.5 metres

C)  7 metres          

D)  5.25 metres

Correct Answer: B

Solution :

[b] Breadth of road \[={{r}_{2}}-\,{{r}_{1}}\] \[{{C}_{2}}-\,{{C}_{1}}=66\] \[\therefore \,\,2\pi {{r}_{2}}=2\pi {{r}_{1}}=66\] \[\Rightarrow 2\pi \,\,({{r}_{2}}-\,{{r}_{1}})=66\] \[\Rightarrow {{r}_{2}}-\,{{r}_{1}}=\frac{66}{2\pi }=\frac{66\times 7}{2\times 22}=10.5\,\,metre\]