A person observed that he required 30 s time to cross a circular ground along its diameter than to cover it once along the boundary. If his speed was 30m/min, than the radius of the circular ground is (take π = 22/7)
Correct Answer: 3.5 m
Explanation:
Let the radius of circular field = r m.
Speed of person in m/s = 30/60 = 1/2m/s
According to the question,
[(2πr) /(1/2)] - [(2r)/(1/2)] = 30
⇒ 4πr - 4r = 30
⇒ [4 x (22/7) - 4]r =30
⇒ (125 - 4)r = 30
⇒ (8.5)r = 30
⇒ r = 30/8.5 = 3.5 m
